Method of transmitting uplink signal from user equipment in a wireless communication system supporting unlicensed band and apparatus supporting the same

ABSTRACT

Disclosed herein is a method of transmitting a UL signal from a user equipment (UE) in a wireless communication system supporting an unlicensed band and apparatuses for supporting the same. More specifically, the present invention provides an embodiment in which the UE performs autonomous uplink transmission and scheduled uplink transmission through the unlicensed band, a method of adjusting contention window size when the UE perform the autonomous uplink transmission through the unlicensed band, and an embodiment of performing the autonomous uplink transmission based on the method.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/248,618, filed on Jan. 15, 2019, now allowed, which is a continuationof International Application No. PCT/KR2018/008886, filed on Aug. 6,2018, which claims the benefit of U.S. Provisional Application No.62/541,107, filed on Aug. 4, 2017, 62/543,965, filed on Aug. 10, 2017,62/564,186, filed on Sep. 27, 2017, 62/570,591, filed on Oct. 10, 2017,62/584,124, filed on Nov. 10, 2017, 62/587,437, filed on Nov. 16, 2017and 62/627,623, filed on Feb. 7, 2018, which are all hereby incorporatedby reference herein in their entirety.

TECHNICAL FIELD

The following description relates to a wireless communication system,and more particularly, to a method of transmitting uplink signals from auser equipment (UE) in a wireless communication system supporting anunlicensed band and apparatuses supporting the same.

BACKGROUND ART

Wireless access systems have been widely deployed to provide varioustypes of communication services such as voice or data. In general, awireless access system is a multiple access system that supportscommunication of multiple users by sharing available system resources (abandwidth, transmission power, etc.) among them. For example, multipleaccess systems include a Code Division Multiple Access (CDMA) system, aFrequency Division Multiple Access (FDMA) system, a Time DivisionMultiple Access (TDMA) system, an Orthogonal Frequency Division MultipleAccess (OFDMA) system, and a Single Carrier Frequency Division MultipleAccess (SC-FDMA) system.

As a number of communication devices have required higher communicationcapacity, the necessity of the mobile broadband communication muchimproved than the existing radio access technology (RAT) has increased.In addition, massive machine type communications (MTC) capable ofproviding various services at anytime and anywhere by connecting anumber of devices or things to each other has been considered in thenext generation communication system. Moreover, a communication systemdesign capable of supporting services/UEs sensitive to reliability andlatency has been discussed.

As described above, the introduction of the next generation RATconsidering the enhanced mobile broadband communication, massive MTC,Ultra-reliable and low latency communication (URLLC), and the like hasbeen discussed.

DISCLOSURE Technical Problem

An object of the present invention is to provide a method oftransmitting uplink signals in a wireless communication systemsupporting an unlicensed band and apparatuses supporting the same.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present disclosure are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present disclosure could achieve will be more clearlyunderstood from the following detailed description.

Technical Solution

The present invention provides a method of transmitting uplink signalsfrom a user equipment (UE) to a base station in a wireless communicationsystem supporting an unlicensed band and an apparatus supporting thesame.

In one aspect of the present invention, provided herein is a method oftransmitting uplink signals from a user equipment (UE) to a base stationin a wireless communication system supporting an unlicensed band, themethod including receiving downlink control information (DCI) schedulinguplink transmission immediately after activated autonomous uplink (AUL)transmission, in a time domain, and performing the AUL transmission andthe uplink transmission through the unlicensed band based on a firstmethod or a second method, wherein the first method corresponds to amethod that the UE terminates ongoing AUL transmission a certain timeinterval before the uplink transmission and performs the uplinktransmission, and wherein the second method corresponds to a method thatthe UE performs the AUL transmission and the uplink transmissioncontinuously.

Herein, the certain time interval may correspond to an N (where N is anatural number) symbol interval.

Herein, when a priority class of the AUL transmission may be larger thanor equal to a priority class of the uplink transmission, and a sum ofdurations of the AUL transmission and the uplink transmission may besmaller than a maximum channel occupancy time (MCOT) corresponding tothe priority class of the AUL transmission, the UE may perform the AULtransmission and the uplink transmission based on the second method.

In the configuration above, when the UE performs the AUL transmissionand the uplink transmission based on the first method, the UE mayperform the AUL transmission based on a first channel access procedure(CAP) for the AUL transmission and the uplink transmission based on asecond CAP for the uplink transmission.

Alternatively, when the UE performs the AUL transmission and the uplinktransmission based on the second method, the UE may perform the AULtransmission and the uplink transmission continuously based on a channelaccess procedure (CAP) for the AUL transmission.

In the configuration above, a first DCI activating first AULtransmission and a second DCI releasing the first AUL transmission maybe distinguished from a third DCI including acknowledgement informationcorresponding to the first AUL transmission based on a value of a firstfield.

In this case, the first field may correspond to a physical uplink sharedchannel (PUSCH) trigger A field.

In addition, the first DCI may be distinguished from the second DCIbased on a value of a second field. Herein, the second field maycorrespond to a timing offset field.

In this case, the first DCI, the second DCI and the third DCI may havean identical size.

In addition, the first DCI, the second DCI and the third DCI may bescrambled by a radio network temporary identifier (RNTI) different froma cell-RNTI (C-RNTI).

In another aspect of the present invention, provided herein is a userequipment (UE) for transmitting uplink signals to a base station in awireless communication system supporting an unlicensed band, the UEincluding a transmitter, a receiver, and a processor operativelyconnected to the transmitter and the receiver, wherein the processor isconfigured to receive downlink control information (DCI) schedulinguplink transmission immediately after activated autonomous uplink (AUL)transmission, in a time domain, and perform the AUL transmission and theuplink transmission through the unlicensed band based on a first methodor a second method, wherein the first method corresponds to a methodthat the UE terminates ongoing AUL transmission a certain time intervalbefore the uplink transmission and performs the uplink transmission, andwherein the second method corresponds to a method that the UE performsthe AUL transmission and the uplink transmission continuously.

In still another aspect of the present invention, provided herein is amethod of transmitting uplink signals from a user equipment (UE) to abase station in a wireless communication system supporting an unlicensedband, the method including performing activated first autonomous uplink(AUL) transmission through the unlicensed band, when downlink controlinformation (DCI) including an uplink grant scheduling uplinktransmission or acknowledgement information is not received during acertain time after the first AUL transmission, increasing contentionwindow sizes (CWSs) corresponding to all channel access priorityclasses, and performing activated second AUL transmission through theunlicensed band based on the increased CWSs.

Herein, the DCI may correspond to DCI including an uplink grant forscheduling a retransmission with respect to the first AUL transmissionor acknowledgment information with respect to the first AULtransmission.

In addition, the certain time may correspond to one or more subframes.

Additionally, when the first AUL transmission or the second AULtransmission is performed in a plurality of cells, starting positions ofthe first AUL transmission or the second AUL transmission in theplurality of cells may be configured to be identical.

In the configuration above, the UE may perform the first AULtransmission based on a first channel access procedure (CAP) for thefirst AUL transmission, and wherein the UE may perform the second AULtransmission based on a second CAP for the second AUL transmission, theincreased CWSs being applied to the second CAP.

In the configuration above, a first DCI activating the first AULtransmission and a second DCI releasing the first AUL transmission maybe distinguished from a third DCI including acknowledgement informationcorresponding to the first AUL transmission based on a value of a firstfield.

Herein, the first field may correspond to a physical uplink sharedchannel (PUSCH) trigger A field.

In addition, the first DCI may be distinguished from the second DCIbased on a value of a second field. Herein, the second field maycorrespond to a timing offset field.

Herein, the first DCI, the second DCI and the third DCI may have anidentical size.

In addition, the first DCI, the second DCI and the third DCI may bescrambled by a radio network temporary identifier (RNTI) different froma cell-RNTI (C-RNTI).

In yet another aspect of the present invention, provided herein is auser equipment (UE) for transmitting uplink signals to a base station ina wireless communication system supporting an unlicensed band, the UEincluding a transmitter, a receiver, and a processor operativelyconnected to the transmitter and the receiver, wherein the processor isconfigured to perform activated first autonomous uplink (AUL)transmission through the unlicensed band, increase, when downlinkcontrol information (DCI) including an uplink grant scheduling uplinktransmission or acknowledgement information is not received during acertain time after the first AUL transmission, contention window sizes(CWSs) corresponding to all channel access priority classes, and performactivated second AUL transmission through the unlicensed band based onthe increased CWSs.

It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure areexemplary and explanatory and are intended to provide furtherexplanation of the disclosure as claimed.

Advantageous Effects

As is apparent from the above description, the embodiments of thepresent disclosure have the following effects.

According to the present invention, a user equipment (UE) mayefficiently perform autonomous uplink (AUL) transmission and scheduledUL transmission/reception.

More specifically, according to the present invention, the UE mayminimize interference to other transmission nodes and a contention-basedchannel access procedure for signal transmission in the unlicensed bandand perform activated AUL transmission and uplink transmission scheduledthrough a UL grant.

In addition, according to the present invention, downlink controlinformation activating/deactivating the AUL transmission or includingacknowledgment information with respect to the AUL transmission may bedistinguished from other downlink control information.

Further, according to the present invention, the UE may conservativelyadjust a contention window size for the AUL transmission.

The effects that can be achieved through the embodiments of the presentinvention are not limited to what has been particularly describedhereinabove and other effects which are not described herein can bederived by those skilled in the art from the following detaileddescription. That is, it should be noted that the effects which are notintended by the present invention can be derived by those skilled in theart from the embodiments of the present invention.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, provide embodiments of the presentinvention together with detail explanation. Yet, a technicalcharacteristic of the present invention is not limited to a specificdrawing. Characteristics disclosed in each of the drawings are combinedwith each other to configure a new embodiment. Reference numerals ineach drawing correspond to structural elements.

FIG. 1 is a diagram illustrating physical channels and a signaltransmission method using the physical channels;

FIG. 2 is a diagram illustrating exemplary radio frame structures;

FIG. 3 is a diagram illustrating an exemplary resource grid for theduration of a downlink slot;

FIG. 4 is a diagram illustrating an exemplary structure of an uplinksubframe;

FIG. 5 is a diagram illustrating an exemplary structure of a downlinksubframe;

FIG. 6 is a diagram illustrating a self-contained slot structureapplicable to the present invention;

FIGS. 7 and 8 are diagrams illustrating representative connectionmethods for connecting TXRUs to antenna elements;

FIG. 9 is a schematic diagram illustrating a hybrid beamformingstructure according to an embodiment of the present invention from theperspective of TXRUs and physical antennas;

FIG. 10 is a diagram schematically illustrating the beam sweepingoperation for synchronization signals and system information during adownlink (DL) transmission process according to an embodiment of thepresent invention;

FIG. 11 is a diagram illustrating an example of a CA environment in awireless communication system supporting an unlicensed band;

FIG. 12 is a diagram illustrating a CAP for unlicensed band transmissionapplicable to the present invention;

FIG. 13 is a diagram illustrating a partial TTI or a partial subframeapplicable to the present invention;

FIG. 14 is a diagram schematically illustrating an AUL transmissionoperation of a UE according to the present invention;

FIGS. 15 and 16 are diagrams schematically illustrating an operation ofadjusting a contention window size (CWS) of a UE according to thepresent invention;

FIG. 17 is a diagram illustrating the operation of a UE according to anembodiment of the present invention;

FIG. 18 is a diagram illustrating the operation of the UE according toanother embodiment of the present invention;

FIG. 19 is a flowchart illustrating a method of transmitting an uplinksignal from a UE through an unlicensed band according to an embodimentof the present invention;

FIG. 20 is a flowchart illustrating a method of transmitting an uplinksignal from a UE through an unlicensed band according to an embodimentof the present invention.

FIG. 21 is a diagram illustrating a configuration of a UE and a basestation in which the proposed embodiments may be implemented.

BEST MODE

The embodiments of the present disclosure described below arecombinations of elements and features of the present disclosure inspecific forms. The elements or features may be considered selectiveunless otherwise mentioned. Each element or feature may be practicedwithout being combined with other elements or features. Further, anembodiment of the present disclosure may be constructed by combiningparts of the elements and/or features. Operation orders described inembodiments of the present disclosure may be rearranged. Someconstructions or elements of any one embodiment may be included inanother embodiment and may be replaced with corresponding constructionsor features of another embodiment.

In the description of the attached drawings, a detailed description ofknown procedures or steps of the present disclosure will be avoided lestit should obscure the subject matter of the present disclosure. Inaddition, procedures or steps that could be understood to those skilledin the art will not be described either.

Throughout the specification, when a certain portion “includes” or“comprises” a certain component, this indicates that other componentsare not excluded and may be further included unless otherwise noted. Theterms “unit”, “-or/er” and “module” described in the specificationindicate a unit for processing at least one function or operation, whichmay be implemented by hardware, software or a combination thereof. Inaddition, the terms “a or an”, “one”, “the” etc. may include a singularrepresentation and a plural representation in the context of the presentdisclosure (more particularly, in the context of the following claims)unless indicated otherwise in the specification or unless contextclearly indicates otherwise.

In the embodiments of the present disclosure, a description is mainlymade of a data transmission and reception relationship between a BaseStation (BS) and a User Equipment (UE). A BS refers to a terminal nodeof a network, which directly communicates with a UE. A specificoperation described as being performed by the BS may be performed by anupper node of the BS.

Namely, it is apparent that, in a network comprised of a plurality ofnetwork nodes including a BS, various operations performed forcommunication with a UE may be performed by the BS, or network nodesother than the BS. The term ‘BS’ may be replaced with a fixed station, aNode B, an evolved Node B (eNode B or eNB), gNode B (gNB), an AdvancedBase Station (ABS), an access point, etc.

In the embodiments of the present disclosure, the term terminal may bereplaced with a UE, a Mobile Station (MS), a Subscriber Station (SS), aMobile Subscriber Station (MSS), a mobile terminal, an Advanced MobileStation (AMS), etc.

A transmission end is a fixed and/or mobile node that provides a dataservice or a voice service and a reception end is a fixed and/or mobilenode that receives a data service or a voice service. Therefore, a UEmay serve as a transmission end and a BS may serve as a reception end,on an UpLink (UL). Likewise, the UE may serve as a reception end and theBS may serve as a transmission end, on a DownLink (DL).

The embodiments of the present disclosure may be supported by standardspecifications disclosed for at least one of wireless access systemsincluding an Institute of Electrical and Electronics Engineers (IEEE)802.xx system, a 3rd Generation Partnership Project (3GPP) system, a3GPP Long Term Evolution (LTE) system, 3GPP 5G NR system, and a 3GPP2system. In particular, the embodiments of the present disclosure may besupported by the standard specifications, 3GPP TS 36.211, 3GPP TS36.212, 3GPP TS 36.213, 3GPP TS 36.321, 3GPP TS 36.331, 3GPP TS 38.211,3GPP TS 38.212, 3GPP TS 38.213, 3GPP TS 38.321 and 3GPP TS 38.331. Thatis, the steps or parts, which are not described to clearly reveal thetechnical idea of the present disclosure, in the embodiments of thepresent disclosure may be explained by the above standardspecifications. All terms used in the embodiments of the presentdisclosure may be explained by the standard specifications.

Reference will now be made in detail to the embodiments of the presentdisclosure with reference to the accompanying drawings. The detaileddescription, which will be given below with reference to theaccompanying drawings, is intended to explain exemplary embodiments ofthe present disclosure, rather than to show the only embodiments thatcan be implemented according to the disclosure.

The following detailed description includes specific terms in order toprovide a thorough understanding of the present disclosure. However, itwill be apparent to those skilled in the art that the specific terms maybe replaced with other terms without departing the technical spirit andscope of the present disclosure.

Hereinafter, 3GPP LTE/LTE-A systems and 3GPP NR system are explained,which are examples of wireless access systems.

The embodiments of the present disclosure can be applied to variouswireless access systems such as Code Division Multiple Access (CDMA),Frequency Division Multiple Access (FDMA), Time Division Multiple Access(TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), SingleCarrier Frequency Division Multiple Access (SC-FDMA), etc.

CDMA may be implemented as a radio technology such as UniversalTerrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented asa radio technology such as Global System for Mobile communications(GSM)/General packet Radio Service (GPRS)/Enhanced Data Rates for GSMEvolution (EDGE). OFDMA may be implemented as a radio technology such asIEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Evolved UTRA(E-UTRA), etc.

UTRA is a part of Universal Mobile Telecommunications System (UMTS).3GPP LTE is a part of Evolved UMTS (E-UMTS) using E-UTRA, adopting OFDMAfor DL and SC-FDMA for UL. LTE-Advanced (LTE-A) is an evolution of 3GPPLTE.

In order to clarify the technical features of the present invention,embodiments of the present invention are described mainly focusing onthe 3GPP LTE/LTE-A system and the 3GPP NR system. It should be noted,however, that the embodiments are applicable even to the IEEE 802.16e/msystem and the like.

1. 3GPP LTE/LTE-A System

1.1. Physical Channels and Signal Transmission and Reception MethodUsing the Same

In a wireless access system, a UE receives information from an eNB on aDL and transmits information to the eNB on a UL. The informationtransmitted and received between the UE and the eNB includes generaldata information and various types of control information. There aremany physical channels according to the types/usages of informationtransmitted and received between the eNB and the UE.

FIG. 1 illustrates physical channels and a general signal transmissionmethod using the physical channels, which may be used in embodiments ofthe present disclosure.

When a UE is powered on or enters a new cell, the UE performs initialcell search (S11). The initial cell search involves acquisition ofsynchronization to an eNB. Specifically, the UE synchronizes its timingto the eNB and acquires information such as a cell Identifier (ID) byreceiving a Primary Synchronization Channel (P-SCH) and a SecondarySynchronization Channel (S-SCH) from the eNB.

Then the UE may acquire information broadcast in the cell by receiving aPhysical Broadcast Channel (PBCH) from the eNB.

During the initial cell search, the UE may monitor a DL channel state byreceiving a Downlink Reference Signal (DL RS).

After the initial cell search, the UE may acquire more detailed systeminformation by receiving a Physical Downlink Control Channel (PDCCH) andreceiving a Physical Downlink Shared Channel (PDSCH) based oninformation of the PDCCH (S12).

To complete connection to the eNB, the UE may perform a random accessprocedure with the eNB (S13 to S16). In the random access procedure, theUE may transmit a preamble on a Physical Random Access Channel (PRACH)(S13) and may receive a PDCCH and a PDSCH associated with the PDCCH(S14). In the case of contention-based random access, the UE mayadditionally perform a contention resolution procedure includingtransmission of an additional PRACH (S15) and reception of a PDCCHsignal and a PDSCH signal corresponding to the PDCCH signal (S16).

After the above procedure, the UE may receive a PDCCH and/or a PDSCHfrom the eNB (S17) and transmit a Physical Uplink Shared Channel (PUSCH)and/or a Physical Uplink Control Channel (PUCCH) to the eNB (S18), in ageneral UL/DL signal transmission procedure.

Control information that the UE transmits to the eNB is genericallycalled Uplink Control Information (UCI). The UCI includes a HybridAutomatic Repeat and reQuest Acknowledgement/Negative Acknowledgement(HARQ-ACK/NACK), a Scheduling Request (SR), a Channel Quality Indicator(CQI), a Precoding Matrix Index (PMI), a Rank Indicator (RI), etc.

In the LTE system, UCI is generally transmitted on a PUCCH periodically.However, if control information and traffic data should be transmittedsimultaneously, the control information and traffic data may betransmitted on a PUSCH. In addition, the UCI may be transmittedaperiodically on the PUSCH, upon receipt of a request/command from anetwork.

1.2. Resource Structure

FIG. 2 illustrates exemplary radio frame structures used in embodimentsof the present disclosure.

FIG. 2(a) illustrates frame structure type 1. Frame structure type 1 isapplicable to both a full Frequency Division Duplex (FDD) system and ahalf FDD system.

One radio frame is 10 ms (Tf=307200·Ts) long, including equal-sized 20slots indexed from 0 to 19. Each slot is 0.5 ms (Tslot=15360·Ts) long.One subframe includes two successive slots. An ith subframe includes2ith and (2i+1)th slots. That is, a radio frame includes 10 subframes. Atime required for transmitting one subframe is defined as a TransmissionTime Interval (TTI). Ts is a sampling time given as Ts=1/(15kHz×2048)=3.2552×10-8 (about 33 ns). One slot includes a plurality ofOrthogonal Frequency Division Multiplexing (OFDM) symbols or SC-FDMAsymbols in the time domain by a plurality of Resource Blocks (RBs) inthe frequency domain.

A slot includes a plurality of OFDM symbols in the time domain. SinceOFDMA is adopted for DL in the 3GPP LTE system, one OFDM symbolrepresents one symbol period. An OFDM symbol may be called an SC-FDMAsymbol or symbol period. An RB is a resource allocation unit including aplurality of contiguous subcarriers in one slot.

In a full FDD system, each of 10 subframes may be used simultaneouslyfor DL transmission and UL transmission during a 10-ms duration. The DLtransmission and the UL transmission are distinguished by frequency. Onthe other hand, a UE cannot perform transmission and receptionsimultaneously in a half FDD system.

The above radio frame structure is purely exemplary. Thus, the number ofsubframes in a radio frame, the number of slots in a subframe, and thenumber of OFDM symbols in a slot may be changed.

FIG. 2(b) illustrates frame structure type 2. Frame structure type 2 isapplied to a Time Division Duplex (TDD) system. One radio frame is 10 ms(Tf=307200·Ts) long, including two half-frames each having a length of 5ms (=153600·Ts) long. Each half-frame includes five subframes each being1 ms (=30720·Ts) long. An ith subframe includes 2ith and (2i+1)th slotseach having a length of 0.5 ms (Tslot=15360·Ts). Ts is a sampling timegiven as Ts=1/(15 kHz×2048)=3.2552×10−8 (about 33 ns).

A type-2 frame includes a special subframe having three fields, DownlinkPilot Time Slot (DwPTS), Guard Period (GP), and Uplink Pilot Time Slot(UpPTS). The DwPTS is used for initial cell search, synchronization, orchannel estimation at a UE, and the UpPTS is used for channel estimationand UL transmission synchronization with a UE at an eNB. The GP is usedto cancel UL interference between a UL and a DL, caused by themulti-path delay of a DL signal.

[Table 1] below lists special subframe configurations (DwPTS/GP/UpPTSlengths).

TABLE 1 Normal cyclic prefix in downlink Extended cyclic prefix indownlink UpPTS UpPTS Normal Extended Normal Extended Special subframecyclic prefix cyclic prefix cyclic prefix cyclic prefix configurationDwPTS in uplink in uplink DwPTS in uplink in uplink 0  6592 · T_(s) 2192· T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s) 1 19760 ·T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 · T_(s) 25600· T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 · T_(s) 5  6592· T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 · T_(s) 23040 ·T_(s) 7 21952 · T_(s) 8 24144 · T_(s) — — —

In addition, in the LTE Rel-13 system, it is possible to newly configurethe configuration of special subframes (i.e., the lengths ofDwPTS/GP/UpPTS) by considering the number of additional SC-FDMA symbols,X, which is provided by the higher layer parameter named “srs-UpPtsAdd”(if this parameter is not configured, X is set to 0). In the LTE Rel-14system, specific subframe configuration #10 is newly added. The UE isnot expected to be configured with 2 additional UpPTS SC-FDMA symbolsfor special subframe configurations {3, 4, 7, 8} for normal cyclicprefix in downlink and special subframe configurations {2, 3, 5, 6} forextended cyclic prefix in downlink and 4 additional UpPTS SC-FDMAsymbols for special subframe configurations {1, 2, 3, 4, 6, 7, 8} fornormal cyclic prefix in downlink and special subframe configurations {1,2, 3, 5, 6} for extended cyclic prefix in downlink.)

TABLE 2 Normal cyclic prefix in downlink Extended cyclic prefix indownlink UpPTS UpPTS Normal Extended Normal Extended Special subframecyclic prefix cyclic prefix cyclic prefix cyclic prefix configurationDwPTS in uplink in uplink DwPTS in uplink in uplink 0  6592 · T_(s) (1 +X) · 2192 · T_(s) (1 + X) · 2560 · T_(s)  7680 · T_(s) (1 + X) · 2192 ·T_(s) (1 + X) · 2560 · T_(s) 1 19760 · T_(s) 20480 · T_(s) 2 21952 ·T_(s) 23040 · T_(s) 3 24144 · T_(s) 25600 · T_(s) 4 26336 · T_(s)  7680· T_(s) (2 + X) · 2192 · T_(s) (2 + X) · 2560 · T_(s) 5  6592 · T_(s)(2 + X) · 2192 · T_(s) (2 + X) · 2560 · T_(s) 20480 · T_(s) 6 19760 ·T_(s) 23040 · T_(s) 7 21952 · T_(s) 12800 · T_(s) 8 24144 · T_(s) — — —9 13168 · T_(s) — — — 10 13168 · T_(s) 13152 · T_(s) 12800 · T_(s) — — —

FIG. 3 illustrates an exemplary structure of a DL resource grid for theduration of one DL slot, which may be used in embodiments of the presentdisclosure.

Referring to FIG. 3, a DL slot includes a plurality of OFDM symbols inthe time domain. One DL slot includes 7 OFDM symbols in the time domainand an RB includes 12 subcarriers in the frequency domain, to which thepresent disclosure is not limited.

Each element of the resource grid is referred to as a Resource Element(RE). An RB includes 12×7 REs. The number of RBs in a DL slot, NDLdepends on a DL transmission bandwidth.

FIG. 4 illustrates a structure of a UL subframe which may be used inembodiments of the present disclosure.

Referring to FIG. 4, a UL subframe may be divided into a control regionand a data region in the frequency domain. A PUCCH carrying UCI isallocated to the control region and a PUSCH carrying user data isallocated to the data region. To maintain a single carrier property, aUE does not transmit a PUCCH and a PUSCH simultaneously. A pair of RBsin a subframe are allocated to a PUCCH for a UE. The RBs of the RB pairoccupy different subcarriers in two slots. Thus it is said that the RBpair frequency-hops over a slot boundary.

FIG. 5 illustrates a structure of a DL subframe that may be used inembodiments of the present disclosure.

Referring to FIG. 5, up to three OFDM symbols of a DL subframe, startingfrom OFDM symbol 0 are used as a control region to which controlchannels are allocated and the other OFDM symbols of the DL subframe areused as a data region to which a PDSCH is allocated. DL control channelsdefined for the 3GPP LTE system include a Physical Control FormatIndicator Channel (PCFICH), a PDCCH, and a Physical Hybrid ARQ IndicatorChannel (PHICH).

The PCFICH is transmitted in the first OFDM symbol of a subframe,carrying information about the number of OFDM symbols used fortransmission of control channels (i.e. the size of the control region)in the subframe. The PHICH is a response channel to a UL transmission,delivering an HARQ ACK/NACK signal. Control information carried on thePDCCH is called Downlink Control Information (DCI). The DCI transportsUL resource assignment information, DL resource assignment information,or UL Transmission (Tx) power control commands for a UE group.

2. New Radio Access Technology System

As a number of communication devices have required higher communicationcapacity, the necessity of the mobile broadband communication muchimproved than the existing radio access technology (RAT) has increased.In addition, massive machine type communications (MTC) capable ofproviding various services at anytime and anywhere by connecting anumber of devices or things to each other has also been required.Moreover, a communication system design capable of supportingservices/UEs sensitive to reliability and latency has been proposed.

As the new RAT considering the enhanced mobile broadband communication,massive MTC, Ultra-reliable and low latency communication (URLLC), andthe like, a new RAT system has been proposed. In the present invention,the corresponding technology is referred to as the new RAT or new radio(NR) for convenience of description.

2.1. Numerologies

The NR system to which the present invention is applicable supportsvarious OFDM numerologies shown in the following table. In this case,the value of μ and cyclic prefix information per carrier bandwidth partcan be signaled in DL and UL, respectively. For example, the value of μand cyclic prefix information per downlink carrier bandwidth part may besignaled though DL-BWP-mu and DL-MWP-cp corresponding to higher layersignaling. As another example, the value of μ and cyclic prefixinformation per uplink carrier bandwidth part may be signaled thoughUL-BWP-mu and UL-MWP-cp corresponding to higher layer signaling.

TABLE 3 μ Δf = 2^(μ) · 15[kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120 Normal 4 240 Normal

2.2 Frame Structure

DL and UL transmission are configured with frames with a length of 10ms. Each frame may be composed of ten subframes, each having a length of1 ms. In this case, the number of consecutive OFDM symbols in eachsubframe is N_(symb) ^(subframe, μ)=N_(symb) ^(slot)N_(slot)^(subframe, μ).

In addition, each subframe may be composed of two half-frames with thesame size. In this case, the two half-frames are composed of subframes 0to 4 and subframes 5 to 9, respectively.

Regarding the subcarrier spacing μ, slots may be numbered within onesubframe in ascending order like n_(s) ^(μ)∈{0, . . . , N_(slot)^(subframe, μ)−1} and may also be numbered within a frame in ascendingorder like n_(s,f) ^(μ)∈{0, . . . , N_(slot) ^(frame, μ)−1}. In thiscase, the number of consecutive OFDM symbols in one slot (N_(symb)^(slot)) may be determined as shown in the following table according tothe cyclic prefix. The start slot (s) of one subframe is aligned withthe start OFDM symbol (n_(s) ^(μ)N_(symb) ^(slot)) of the same subframein the time dimension. Table 4 shows the number of OFDM symbols in eachslot/frame/subframe in the case of the normal cyclic prefix, and Table 5shows the number of OFDM symbols in each slot/frame/subframe in the caseof the extended cyclic prefix.

TABLE 4 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16 5 14 320 32

TABLE 5 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)2 12 40 4

In the NR system to which the present invention can be applied, aself-contained slot structure can be applied based on theabove-described slot structure.

FIG. 6 is a diagram illustrating a self-contained slot structureapplicable to the present invention.

In FIG. 6, the hatched area (e.g., symbol index=0) indicates a downlinkcontrol region, and the black area (e.g., symbol index=13) indicates anuplink control region. The remaining area (e.g., symbol index=1 to 13)can be used for DL or UL data transmission.

Based on this structure, the eNB and UE can sequentially perform DLtransmission and UL transmission in one slot. That is, the eNB and UEcan transmit and receive not only DL data but also UL ACK/NACK inresponse to the DL data in one slot. Consequently, due to such astructure, it is possible to reduce a time required until dataretransmission in case a data transmission error occurs, therebyminimizing the latency of the final data transmission.

In this self-contained slot structure, a predetermined length of a timegap is required for the process of allowing the eNB and UE to switchfrom transmission mode to reception mode and vice versa. To this end, inthe self-contained slot structure, some OFDM symbols at the time ofswitching from DL to UL are set as a guard period (GP).

Although it is described that the self-contained slot structure includesboth the DL and UL control regions, these control regions can beselectively included in the self-contained slot structure. In otherwords, the self-contained slot structure according to the presentinvention may include either the DL control region or the UL controlregion as well as both the DL and UL control regions as shown in FIG. 6.

In addition, for example, the slot may have various slot formats. Inthis case, OFDM symbols in each slot can be divided into downlinksymbols (denoted by ‘D’), flexible symbols (denoted by ‘X’), and uplinksymbols (denoted by ‘U’).

Thus, the UE can assume that DL transmission occurs only in symbolsdenoted by ‘D’ and ‘X’ in the DL slot. Similarly, the UE can assume thatUL transmission occurs only in symbols denoted by ‘U’ and ‘X’ in the ULslot.

2.3. Analog Beamforming

In a millimeter wave (mmW) system, since a wavelength is short, aplurality of antenna elements can be installed in the same area. Thatis, considering that the wavelength at 30 GHz band is 1 cm, a total of100 antenna elements can be installed in a 5*5 cm panel at intervals of0.5 lambda (wavelength) in the case of a 2-dimensional array. Therefore,in the mmW system, it is possible to improve the coverage or throughputby increasing the beamforming (BF) gain using multiple antenna elements.

In this case, each antenna element can include a transceiver unit (TXRU)to enable adjustment of transmit power and phase per antenna element. Bydoing so, each antenna element can perform independent beamforming perfrequency resource.

However, installing TXRUs in all of the about 100 antenna elements isless feasible in terms of cost. Therefore, a method of mapping aplurality of antenna elements to one TXRU and adjusting the direction ofa beam using an analog phase shifter has been considered. However, thismethod is disadvantageous in that frequency selective beamforming isimpossible because only one beam direction is generated over the fullband.

To solve this problem, as an intermediate form of digital BF and analogBF, hybrid BF with B TXRUs that are fewer than Q antenna elements can beconsidered. In the case of the hybrid BF, the number of beam directionsthat can be transmitted at the same time is limited to B or less, whichdepends on how B TXRUs and Q antenna elements are connected.

FIGS. 7 and 8 are diagrams illustrating representative methods forconnecting TXRUs to antenna elements. Here, the TXRU virtualizationmodel represents the relationship between TXRU output signals andantenna element output signals.

FIG. 7 shows a method of connecting TXRUs to sub-arrays. In FIG. 7, oneantenna element is connected to one TXRU.

Meanwhile, FIG. 8 shows a method for connecting all TXRUs to all antennaelements. In FIG. 8, all antenna element are connected to all TXRUs. Inthis case, separate addition units are required to connect all antennaelements to all TXRUs as shown in FIG. 8.

In FIGS. 7 and 8, W indicates a phase vector weighted by an analog phaseshifter. That is, W is a major parameter determining the direction ofthe analog beamforming. In this case, the mapping relationship betweenCSI-RS antenna ports and TXRUs may be 1:1 or 1-to-many.

The configuration shown in FIG. 7 has a disadvantage in that it isdifficult to achieve beamforming focusing but has an advantage in thatall antennas can be configured at low cost.

On the contrary, the configuration shown in FIG. 8 is advantageous inthat beamforming focusing can be easily achieved. However, since allantenna elements are connected to the TXRU, it has a disadvantage ofhigh cost.

When a plurality of antennas are used in the NR system to which thepresent invention is applicable, the hybrid beamforming method obtainedby combining the digital beamforming and analog beamforming can beapplied. In this case, the analog (or radio frequency (RF)) beamformingmeans the operation where precoding (or combining) is performed at theRF end. In the case of the hybrid beamforming, precoding (or combining)is performed at the baseband end and RF end, respectively. Thus, thehybrid beamforming is advantageous in that it guarantees the performancesimilar to the digital beamforming while reducing the number of RFchains and D/A (digital-to-analog) (or A/D (analog-to-digital) zconverters.

For convenience of description, the hybrid beamforming structure can berepresented by N transceiver units (TXRUs) and M physical antennas. Inthis case, the digital beamforming for L data layers to be transmittedby the transmitting end may be represented by the N*L (N by L) matrix.Thereafter, N converted digital signals are converted into analogsignals by the TXRUs, and then the analog beamforming, which may berepresented by the M*N (M by N) matrix, is applied to the convertedsignals.

FIG. 9 is a schematic diagram illustrating a hybrid beamformingstructure according to an embodiment of the present invention from theperspective of TXRUs and physical antennas. In FIG. 9, it is assumedthat the number of digital beams is L and the number of analog beams isN.

Additionally, a method for providing efficient beamforming to UEslocated in a specific area by designing an eNB capable of changinganalog beamforming on a symbol basis has been considered in the NRsystem to which the present invention is applicable. Further, a methodof introducing a plurality of antenna panels where independent hybridbeamforming can be applied by defining N TXRUs and M RF antennas as oneantenna panel has also been considered in the NR system to which thepresent invention is applicable.

When the eNB uses a plurality of analog beams as described above, eachUE has a different analog beam suitable for signal reception. Thus, thebeam sweeping operation where the eNB applies a different analog beamper symbol in a specific subframe (SF) (at least with respect tosynchronization signals, system information, paging, etc.) and thenperform signal transmission in order to allow all UEs to have receptionopportunities has been considered in the NR system to which the presentinvention is applicable.

FIG. 10 is a diagram schematically illustrating the beam sweepingoperation for synchronization signals and system information during adownlink (DL) transmission process according to an embodiment of thepresent invention

In FIG. 10, a physical resource (or channel) for transmitting systeminformation of the NR system to which the present invention isapplicable in a broadcasting manner is referred to as a physicalbroadcast channel (xPBCH). In this case, analog beams belonging todifferent antenna panels can be simultaneously transmitted in onesymbol.

In addition, the introduction of a beam reference signal (BRS)corresponding to the reference signal (RS) to which a single analog beam(corresponding to a specific antenna panel) is applied has beendiscussed as the configuration for measuring a channel per analog beamin the NR system to which the present invention is applicable. The BRScan be defined for a plurality of antenna ports, and each BRS antennaport may correspond to a single analog beam. In this case, unlike theBRS, all analog beams in the analog beam group can be applied to thesynchronization signal or xPBCH unlike the BRS to assist a random UE tocorrectly receive the synchronization signal or xPBCH.

3. Licensed Assisted Access (LAA) System

Hereinafter, methods for transmitting and receiving data in a carrieraggregation environment of an NR or LTE band, which is a licensed band,and a unlicensed band will be described. In the embodiments of thepresent invention, the LAA system refers to a communication system(e.g., an LTE system or an NR system) that supports a CA situation ofthe licensed band and the unlicensed band. Here, as the unlicensed band,a WiFi band or a Bluetooth (BT) band may be used.

Here, LAA may refer to an LTE system or an NR system operating in anunlicensed band. LAA may also refer to a method for transmitting andreceiving data in the unlicensed band in combination with the licensedband.

FIG. 11 is a diagram illustrating an example of a CA environment in awireless communication system supporting an unlicensed band.

Hereinafter, for simplicity, it is assumed that the UE is configured toperform wireless communication in each of the licensed band and theunlicensed band using two component carriers (CCs). Of course, thefollowing methods may be applied even when three or more CCs areconfigured for the UE.

In the embodiments of the present invention, it is assumed that alicensed CC (LCC) is a primary CC (which may be called a PCC or a PCell)and an unlicensed CC (UCC) is a secondary CC (which may be called a SCCor SCell). The embodiments of the present invention are also beapplicable even to a situation in which multiple licensed bands andmultiple unlicensed bands are used in a carrier aggregation manner.Further, the proposed schemes of the present invention are applicablenot only to the 3GPP LTE system and the 3GPP NR system but also tosystems having other characteristics.

FIG. 11 illustrates a case where one base station supports both thelicensed band and the unlicensed band. That is, the UE maytransmit/receive control information and data via a PCC, which is alicensed band, and also transmit/receive control information and datavia the SCC, which is an unlicensed band. The situation shown in FIG. 11is merely one example, and the embodiments of the present invention areapplicable even to a CA environment where one UE accesses multiple basestations.

For example, the UE may configure a PCell with a macro base station (aMacro eNB (M-eNB) or a Macro gNB (M-gNB)), and may configure an SCellwith a small base station (a Small eNB (S-eNB) or a Small gNB (S-gNB)).In this case, the macro base station and the small base station may beconnected over a backhaul network.

In embodiments of the present invention, the unlicensed band may beoperated according to a contention-based random access scheme. In thiscase, channel access procedures for LAA are performed as follows.

3.1. Downlink Channel Access Procedures

An eNB operating LAA Scell(s) (or an unlicensed band) shall perform thedownlink channel access procedure (CAP) described below for cell(s) inwhich the LAA Scell(s) transmission(s) are performed.

3.1.1. Channel Access Procedure for Transmission(s) IncludingPDSCH/PDCCH/EPDCCH

The eNB may transmit a transmission including PDSCH/PDCCH/EPDCCH on acarrier on which LAA Scell(s) transmission(s) are performed, after firstsensing the channel to be idle during the slot durations of a deferdurationTd; and after the counter N is zero in step 4 below. The counterN is adjusted by sensing the channel for additional slot duration(s)according to the steps below:

1) set N=N_(init), where N_(init) is a random number uniformlydistributed between 0 and CW_(p), and go to step 4;

2) if N>0 and the eNB chooses to decrement the counter, set N=N−1;

3) sense the channel for an additional slot duration, and if theadditional slot duration is idle, go to step 4; else, go to step 5;

4) if N=0, stop; else, go to step 2;

5) sense the channel until a busy slot is detected in an additionaldefer duration T_(d) or all the slots of the additional defer durationT_(d) are detected to be idle;

6) if the channel is sensed to be idle during all the slot durations ofthe additional defer duration T_(d), go to step 4; else, go to step 5.

The CAP for transmission including PDSCH/PDCCH/EPDCCH of the eNBdescribed above may be summarized as follows.

FIG. 12 is a diagram illustrating a CAP for unlicensed band transmissionapplicable to the present invention.

For a downlink transmission, a transmission node (e.g., an eNB) mayinitiate a channel access procedure (CAP) to operate in the LAAScell(s), which are unlicensed band cells (S1210).

The eNB may randomly select a backoff counter N within the contentionwindow CW according to step 1. At this time, N is set to an initialvalue N_(init) (S1220). N_(init) is selected as any value from among thevalues between 0 and CW_(p).

Next, if the backoff counter value N is 0 in step 4 (S1230; Y), the eNBterminates the CAP (S1232). Then, the eNB may perform Tx bursttransmission including PDSCH/PDCCH/EPDCCH (S1234). On the other hand, ifthe backoff counter value is not 0 (S1230; N), the eNB decrements thebackoff counter value by 1 according to step 2 (S1240).

Then, the eNB checks whether the channel of the LAA SCell(s) is idle(S1250). If the channel is idle (S1250; Y), the base station checkswhether the backoff counter value is 0 (S1230).

On the contrary, if the channel is not idle in operation S1250 (S1250;N), namely, if the channel is busy, the eNB checks whether the channelis idle during a defer duration T_(d) (25 usec or more) longer than theslot time (e.g., 9 usec) (S1262). If the channel is idle during thedefer duration (S1270; Y), the eNB may resume the CAP.

For example, when the backoff counter value Nina is 10 and it isdetermined that the channel is busy after the backoff counter value isdecreased to 5, the eNB senses the channel during the defer duration todetermine whether the channel is idle. If the channel is idle during thedefer duration, the eNB may perform the CAP again from the backoffcounter value 5 (or 4 after decrementing the backoff counter value by 1)instead of setting the backoff counter value N_(init).

On the other hand, if the channel is busy during the defer duration(S1270; N), the eNB re-performs operation S1260 and checks again whetherthe channel is idle during a new defer duration.

If an eNB has not transmitted a transmission includingPDSCH/PDCCH/EPDCCH on a carrier on which LAA Scell(s) transmission(s)are performed after step 4 in the procedure above, the eNB may transmita transmission including PDSCH/PDCCH/EPDCCH on the carrier if thefollowing conditions are met:

the channel is sensed to be idle at least in a slot duration T_(sl) whenthe eNB is ready to transmit PDSCH/PDCCH/EPDCCH; and the channel hasbeen sensed to be idle during all the slot durations of a defer durationT_(d) immediately before this transmission.

If the channel has not been sensed to be idle in a slot duration T_(sl)when the eNB senses the channel after it is ready to transmit, or if thechannel has been sensed to be not idle during any of the slot durationsof a defer duration T_(d) immediately before the intended transmission,the eNB proceeds to step 1 after sensing the channel to be idle duringthe slot durations of a defer duration T_(d).

The defer duration T_(d) consists of duration T_(f) (=16 us) immediatelyfollowed by m_(p) consecutive slot durations where each slot durationT_(sl) is 9 us, and T_(f) includes an idle slot duration T_(sl) at thestart of T_(f).

A slot duration T_(sl) is considered to be idle if the eNB senses thechannel during the slot duration T_(sl), and the power detected by theeNB for at least 4 us in the slot duration is less than energy detectionthreshold X_(Thresh). Otherwise, the slot duration T_(sl) is consideredto be busy.

CW_(min,p)≤CW_(p)≤CW_(max,p) is the contention window. CW_(p) adjustmentis described in detail in sub clause 3.1.3.

CW_(min,p) and CW_(max,p) chosen before step 1 of the procedure above.

m_(p), CW_(min,p), and CW_(max,p) are based on channel access priorityclass associated with the eNB transmission (see Table 6 below).

X_(Thresh) is adjusted as described in sub clause 3.1.4.

TABLE 6 Channel Access Priority allowed CW_(p) Class (p) m_(p)CW_(min, p) CW_(max, p) T_(mcot, p) sizes 1 1 3 7 2 ms {3, 7} 2 1 7 15 3ms  {7, 15} 3 3 15 63 8 or 10 ms {15, 31, 63} 4 7 15 1023 8 or 10 ms{15, 31, 63, 127, 255, 511, 1023}

If the eNB transmits discovery signal transmission(s) not includingPDSCH/PDCCH/EPDCCH when N>0 in the procedure above, the eNB shall notdecrement the counter N during the slot duration(s) overlapping with thediscovery signal transmission.

The eNB shall not perform continuous transmission on a carrier on whichthe LAA Scell(s) transmission(s) are performed, for a period exceedingT_(mcot,p) as given in Table 6.

For p=3 and p=4 in Table 6, if the absence of any other technologysharing the carrier can be guaranteed on a long term basis (e.g., bylevel of regulation), T_(mcot,p) is set to 10 ms. Otherwise, T_(mcot,p)is set to 8 ms.

3.1.2. Channel Access Procedure for Transmissions Including DiscoverySignal Transmission(s) and not Including PDSCH

An eNB may transmit a transmission including discovery signal but notincluding PDSCH on a carrier on which LAA Scell(s) transmission(s) areperformed immediately after sensing the channel to be idle for at leasta sensing interval T_(drs)=25 us and if the duration of the transmissionis less than 1 ms. Here, T_(drs) consists of a duration T_(f) (=16 us)immediately followed by one slot duration T_(sl)=9 us. T_(f) includes anidle slot duration T_(sl) at the start of T_(f). The channel isconsidered to be idle for Tars, if it is sensed to be idle during theslot durations of T_(drs).

3.1.3. Contention Window Adjustment Procedure

If the eNB transmits transmissions including PDSCH that are associatedwith channel access priority class p on a carrier, the eNB maintains thecontention window value CW_(p) and adjusts CW_(p) before step 1 of theprocedure (i.e., before the CAP) described in sub clause 3.1.1 for thosetransmissions using the following steps:

1> for every priority class p∈{1, 2, 3, 4}, set CW_(p)=CW_(min,p);

2> if at least Z=80% of HARQ-ACK values corresponding to PDSCHtransmission(s) in reference subframe k are determined as NACK, increaseCW_(p) for every priority class p∈{1, 2, 3, 4} to the next higherallowed value and remain in step 2; otherwise, go to step 1.

In other words, if the probability that the HARQ-ACK valuescorresponding to the PDSCH transmission(s) in reference subframe k aredetermined as NACK is at least 80%, the eNB increases the CW values setfor each priority class to the next higher priority class.Alternatively, the eNB maintains the CW values set for each priorityclass as initial values.

Here, reference subframe k is the starting subframe of the most recenttransmission on the carrier made by the eNB, for which at least someHARQ-ACK feedback is expected to be available.

The eNB shall adjust the value of CW_(p) for every priority class p∈{1,2, 3, 4} based on a given reference subframe k only once.

If CW_(p)=CW_(max,p), the next higher allowed value for adjusting CW_(p)is CW_(max,p).

The probability Z that the HARQ-ACK values corresponding to PDSCHtransmission(s) in reference subframe k are determined as NACK may bedetermined in consideration of the followings:

-   -   if the eNB transmission(s) for which HARQ-ACK feedback is        available start in the second slot of subframe k, HARQ-ACK        values corresponding to PDSCH transmission(s) in subframe k+1        are also used in addition to the HARQ-ACK values corresponding        to PDSCH transmission(s) in subframe k.    -   if the HARQ-ACK values correspond to PDSCH transmission(s) on an        LAA SCell that are assigned by (E)PDCCH transmitted on the same        LAA SCell,        -   if no HARQ-ACK feedback is detected for a PDSCH transmission            by the eNB, or if the eNB detects ‘DTX’, ‘NACK/DTX’ or ‘any’            state, it is counted as NACK.    -   if the HARQ-ACK values correspond to PDSCH transmission(s) on an        LAA SCell that are assigned by (E)PDCCH transmitted on another        LAA cell,        -   if the HARQ-ACK feedback for a PDSCH transmission is            detected by the eNB, ‘NACK/DTX’ or ‘any’ state is counted as            NACK, and ‘DTX’ state is ignored.        -   if no HARQ-ACK feedback is detected for a PDSCH transmission            by the eNB,            -   if PUCCH format 1 with channel selection is expected to                be used by the UE, ‘NACK/DTX’ state corresponding to ‘no                transmission’ is counted as NACK, and ‘DTX’ state                corresponding to ‘no transmission’ is ignored.                Otherwise, the HARQ-ACK for the PDSCH transmission is                ignored.        -   if a PDSCH transmission has two codewords, the HARQ-ACK            value of each codeword is considered separately.        -   bundled HARQ-ACK across M subframes is considered as M            HARQ-ACK responses.

If the eNB transmits transmissions including PDCCH/EPDCCH with DCIformat 0A/0B/4A/4B and not including PDSCH that are associated withchannel access priority class p on a channel starting from time to, theeNB maintains the contention window value CW_(p) and adjusts CW_(p)before step 1 of the procedure described in sub clause 3.1.1 for thosetransmissions (i.e., before performing the CAP) using the followingsteps:

1> for every priority class p∈{1, 2, 3, 4}, set CW_(p)=CW_(min,p);

2> if less than 10% of the UL transport blocks scheduled by the eNBusing Type 2 channel access procedure (described in sub clause 3.2.1.2)in the time interval between to and t₀+T_(CO) have been receivedsuccessfully, increase CW_(p) for every priority class p∈{1, 2, 3, 4} tothe next higher allowed value and remain in step 2; otherwise, go tostep 1.

Here, T_(CO) is calculated as described is computed as described insubclause 3.2.1.

If the CW_(p)=CW_(max,p) is consecutively used K times for generation ofN_(init), CW_(p) is reset to CW_(min,p) only for that priority classCW_(p)=CW_(max,p) for which is consecutively used K times for generationof N_(init). K is selected by the eNB from the set of values {1, 2, . .. , 8} for each priority class p∈{1, 2, 3, 4}.

3.1.4. Energy Detection Threshold Adaptation Procedure

An eNB accessing a carrier on which LAA Scell(s) transmission(s) areperformed, shall set the energy detection threshold (X_(Thresh)) to beless than or equal to the maximum energy detection thresholdX_(Thresh_max).

The maximum energy detection threshold X_(Thresh_max) is determined asfollows:

-   -   if the absence of any other technology sharing the carrier can        be guaranteed on a long term basis (e.g., by level of        regulation), then:

${X_{{Thresh}\_\max} = {\min\begin{Bmatrix}{{T_{\max} + {10\mspace{14mu}{dB}}},} \\X_{r}\end{Bmatrix}}},$

-   -   where X_(r) is the energy detection threshold defined by        regulatory requirements in dBm when such requirements are        defined, otherwise X_(r)=T_(max)+10 dB.

Otherwise,

${X_{{Thresh}\_\max} = {\max\begin{Bmatrix}{{{- 72} + {{10 \cdot \log}\; 10\left( {{BWMHz}/20\mspace{14mu}{MHz}} \right){dBm}}},} \\{\min\begin{Bmatrix}{T_{\max},} \\{T_{\max} - T_{A} + \left( {P_{H} + {{10 \cdot \log}\; 10\left( {{BWMHz}\text{/}20\mspace{14mu}{MHz}} \right)} - P_{TX}} \right)}\end{Bmatrix}}\end{Bmatrix}}},$

where each variable is defined as follows:

-   -   T₄=10 dB for transmission(s) including PDSCH;    -   T_(A)=5 dB for transmissions including discovery signal        transmission(s) and not including PDSCH;    -   P_(H)=23 dBm;    -   P_(TX) is the set maximum eNB output power in dBm for the        carrier;        -   eNB uses the set maximum transmission power over a single            carrier irrespective of whether single carrier or            multi-carrier transmission is employed    -   T_(max)(dBm)=10·log 10(3.16228·10⁻⁸ (mW/MHz)·BWMHz (MHz));    -   BWMHz is the single carrier bandwidth in MHz.

3.1.5. Channel Access Procedure for Transmission(s) on Multiple Carriers

An eNB can access multiple carriers on which LAA Scell(s)transmission(s) are performed, according to one of the Type A or Type Bprocedures described below.

3.1.5.1. Type A Multi-Carrier Access Procedures

The eNB shall perform channel access on each carrier C_(i)∈C, accordingto the procedures described in this subclause, where C is a set ofcarriers on which the eNB intends to transmit, and i=0, 1, . . . q−1,and q is the number of carriers on which the eNB intends to transmit.

The counter N described in subclause 3.1.1 (i.e., the counter Nconsidered in the CAP) is determined for each carrier c, and is denotedas N_(c) _(i) . N_(c) _(i) is maintained according to subclause3.1.5.1.1 or 3.1.5.1.2 below.

3.1.5.1.1. Type A1

Counter N as described in subclause 3.1.1 (i.e., the counter Nconsidered in the CAP) is independently determined for each carrier c,and is denoted as N_(c) _(i) .

If the absence of any other technology sharing the carrier can beguaranteed on a long term basis (e.g., by level of regulation), when theeNB ceases transmission on any one carrier c_(j)∈C, for each carrierc_(i) (where c_(i)≠c_(j)), the eNB can resume decrementing N_(c) _(i)when idle slots are detected either after waiting for a duration of4·T_(sl), or after reinitialising N_(c) _(i) .

3.1.5.1.2. Type A2

Counter N is determined as described in subclause 3.1.1 for each carrierc_(j)∈C, and is denoted as N_(c) _(i) , where c_(j) may be the carrierthat has the largest CW_(p) value. For each carrier c_(i), N_(c) _(i)=N_(c) _(j) .

When the eNB ceases transmission on any one carrier for which N_(c) _(i)is determined, the eNB shall reinitialise N_(c) _(i) for all carriers.

3.1.5.2. Type B Multi-Carrier Access Procedure

A carrier c_(j)∈C is selected by the eNB as follows:

-   -   the eNB selects c_(j) by uniformly randomly choosing c_(j) from        C before each transmission on multiple carriers c_(i)∈C; or    -   the eNB selects c_(j) no more frequently than once every 1        second,

where C is a set of carriers on which the eNB intends to transmit, i=0,1, . . . q−1, and q is the number of carriers on which the eNB intendsto transmit.

To transmit on carrier c_(j), the eNB shall perform channel access oncarrier c_(j) according to the procedures described in subclause 3.1.1with the modifications described in 3.1.5.2.1 or 3.1.5.2.2.

To transmit on carrier c_(i)≠c_(j), c_(i)∈C,

for each carrier c_(i), the eNB shall sense the carrier c_(i) for atleast a sensing interval T_(mc)=25 us immediately before thetransmitting on carrier c_(j). And the eNB may transmit on carrier c_(i)immediately after sensing the carrier c, to be idle for at least thesensing interval T_(mc). The carrier c_(i) is considered to be idle forT_(mc) if the channel is sensed to be idle during all the time durationsin which such idle sensing is performed on the carrier c_(j) in giveninterval T_(mc).

The eNB shall not continuously transmit on a carrier c_(i)≠c_(j) (wherec_(i)∈C) for a period exceeding T_(mcot,p) as given in Table 6, wherethe value of T_(mcot,p) is determined using the channel accessparameters used for carrier c_(j).

3.1.5.2.1. Type B1

A single CW_(p) value is maintained for the set of carriers C.

For determining CW_(p) for channel access on carrier c_(j), step 2 ofthe procedure described in sub clause 3.1.3 is modified as follows:

if at least Z=80% of HARQ-ACK values corresponding to PDSCHtransmission(s) in reference subframe k of all carriers c_(i)∈C aredetermined as NACK, increase CW_(p) for every priority class p∈{1, 2, 3,4} to the next higher allowed value; otherwise, go to step 1.

3.1.5.2.2. Type B2

A CW_(p) value is maintained independently for each carrier c, E C usingthe procedure described in subclause 3.1.3. For determining N_(init) forcarrier c_(j), CW_(p) value of carrier c_(j1)∈C is used, where c_(j1) isthe carrier with the largest CW_(p) among all carriers in set C.

3.2. Uplink Channel Access Procedures

A UE and an eNB scheduling UL transmission(s) for the UE shall performthe procedures described below to access the channel(s) on which the LAAScell(s) transmission(s) are performed.

3.2.1. Channel Access Procedure for Uplink Transmission (s)

The UE can access a carrier on which LAA Scell(s) UL transmission(s) areperformed according to one of Type 1 or Type 2 UL channel accessprocedures. Type 1 channel access procedure is described in sub clause3.2.1.1 below. Type 2 channel access procedure is described in subclause 3.2.1.2 below.

If an UL grant scheduling a PUSCH transmission indicates Type 1 channelaccess procedure, the UE shall use Type 1 channel access procedure fortransmitting transmissions including the PUSCH transmission unlessstated otherwise in this sub clause.

If an UL grant scheduling a PUSCH transmission indicates Type 2 channelaccess procedure, the UE shall use Type 2 channel access procedure fortransmitting transmissions including the PUSCH transmission unlessstated otherwise in this sub clause.

The UE shall use Type 1 channel access procedure for SRS (SoundingReference Signal) transmissions not including a PUSCH transmission. ULchannel access priority class p=1 is used for SRS transmissions notincluding a PUSCH.

TABLE 7 Channel Access Priority allowed CW_(p) Class (p) m_(p)CW_(min, p) CW_(max, p) T_(ulmcot, p) sizes 1 2 3 7 2 ms {3, 7} 2 2 7 154 ms  {7, 15} 3 3 15 1023 6 ms or {15, 31, 63, 127, 10 ms 255, 511,1023} 4 7 15 1023 6 ms or {15, 31, 63, 127, 10 ms 255, 511, 1023} NOTE1:For p = 3, 4, T_(ulmcot, p) = 10 ms if the higher layer parameter‘absenceOfAnyOtherTechnology-r14’ indicates TRUE, otherwise,T_(ulmcot, p) = 6 ms. NOTE 2: When T_(ulmcot, p) = 6 ms it maybeincreased to 8 ms by inserting one or more gaps. The minimum duration ofa gap shall be 100 μs. The maximum duration before including any suchgap shall be 6 ms.

If the ‘UL configuration for LAA’ field configures an ‘UL offset’ 1 andan ‘UL duration’ d for subframe n, then

the UE may use channel access Type 2 for transmissions in subframesn+l+i (where i=0, 1, . . . d−1), if the end of UE transmission occurs inor before subframe n+l+d−1.

If the UE scheduled to transmit transmissions including PUSCH in a setof subframes n₀, n₁, . . . , n_(w−1) using PDCCH DCI format 0B/4B, andif the UE cannot access the channel for a transmission in subframen_(k), the UE shall attempt to make a transmission in subframe n_(k+1)according to the channel access type indicated in the DCI, where k∈{0,1, . . . w−2}, and w is the number of scheduled subframes indicated inthe DCI.

If the UE is scheduled to transmit transmissions without gaps includingPUSCH in a set of subframes n₀, n₁, . . . , n_(w−1) using one or morePDCCH DCI format 0A/0B/4A/4B and the UE performs a transmission insubframe n_(k) after accessing the carrier according to one of Type 1 orType 2 channel access procedures, the UE may continue transmission insubframes after n_(k) where k∈{0, 1, . . . w−1}.

If the beginning of UE transmission in subframe n+1 immediately followsthe end of UE transmission in subframe n, the UE is not expected to beindicated with different channel access types for the transmissions inthose subframes.

If the UE is scheduled to perform transmission without gaps in subframesn₀, n₁, . . . , n_(w−1) using one or more PDCCH DCI format 0A/0B/4A/4B,and if the UE has stopped transmitting during or before subframe n_(k1),where k1∈{0, 1, . . . w−2}, and if the channel is sensed by the UE to becontinuously idle after the UE has stopped transmitting, the UE maytransmit in a later subframe n_(k2), where k2∈{1, . . . w−1}, using Type2 channel access procedure. If the channel sensed by the UE is notcontinuously idle after the UE has stopped transmitting, the UE maytransmit in a later subframe n_(k2), where k2∈{1, . . . w−1}, using Type1 channel access procedure with the UL channel access priority classindicated in the DCI corresponding to subframe n_(k2).

If the UE receives an UL grant and the DCI indicates a PUSCHtransmission starting in subframe n using Type 1 channel accessprocedure, and if the UE has an ongoing Type 1 channel access procedurebefore subframe n:

-   -   if the UL channel access priority class value p₁ used for the        ongoing Type 1 channel access procedure is same or larger than        the UL channel access priority class value c₂ indicated in the        DCI, the UE may transmit the PUSCH transmission in response to        the UL grant by accessing the carrier by using the ongoing Type        1 channel access procedure;    -   if the UL channel access priority class value p₁ used for the        ongoing Type 1 channel access procedure is smaller than the UL        channel access priority class value p₂ indicated in the DCI, the        UE shall terminate the ongoing channel access procedure.

If the UE is scheduled to transmit on a set of carriers C in subframe n,and if the UL grants scheduling PUSCH transmissions on the set ofcarriers C indicate Type 1 channel access procedure, and if the same‘PUSCH starting position’ is indicated for all carriers in the set ofcarriers C, and if the carrier frequencies of the set of carriers C is asubset of one of the sets of predefined carrier frequencies,

-   -   the UE may transmit on carrier c_(i)∈C using Type 2 channel        access procedure.        -   if Type 2 channel access procedure is performed on carrier            c_(i) immediately before the UE transmission on carrier            c_(j)∈C, where i≠j, and        -   if the UE has accessed carrier c_(j) using Type 1 channel            access procedure,        -   carrier c_(j) is selected by the UE uniformly randomly from            the set of carriers C before performing Type 1 channel            access procedure on any carrier in the set of carriers C.

A base station may indicate Type 2 channel access procedure in the DCIof an UL grant scheduling transmission(s) including PUSCH on a carrierin subframe n when the base station has transmitted on the carrieraccording to the channel access procedure described in clause 3.1.1.

Alternatively, a base station may indicate using the ‘UL Configurationfor LAA’ field that the UE may perform a Type 2 channel access procedurefor transmissions(s) including PUSCH on a carrier in subframe n when thebase station has transmitted on the carrier according to the channelaccess procedure described in clause 3.1.1.

Alternatively, a base station may schedule transmissions including PUSCHon a carrier in subframe n, that follows a transmission by the basestation on that carrier with a duration of T_(short_ul)=25 us, ifsubframe n occurs within the time interval starting at t₀ and ending att₀+T_(CO), where T_(CO)=T_(mcot,p)+T_(g), where each variable may bedefined as follows:

-   -   t₀ is the time instant when the base station has started        transmission;    -   T_(mcot,p) is determined by the base station as described in        clause 3.1;    -   T_(g) is the total duration of all gaps of duration greater than        25 us that occur between the DL transmission of the base station        and UL transmissions scheduled by the base station, and between        any two UL transmissions scheduled by the base station starting        from t₀.

The base station shall schedule UL transmissions between t₀ andt₀+T_(CO) in contiguous subframes if they can be scheduled contiguously.

For an UL transmission on a carrier that follows a transmission by thebase station on that carrier within a duration of T_(short_ul)=25 us,the UE may use Type 2 channel access procedure for the UL transmission.

If the base station indicates Type 2 channel access procedure for the UEin the DCI, the base station indicates the channel access priority classused to obtain access to the channel in the DCI.

3.2.1.1. Type 1 UL Channel Access Procedure

The UE may perform the transmission using Type 1 channel accessprocedure after sensing the channel to be idle during the slot durationsof a defer duration T_(d); and after the counter N is zero in step 4.The counter N is adjusted by sensing the channel for additional slotduration(s) according to the steps described below:

1) set N=N_(init), where N_(init) is a random number uniformlydistributed between 0 and CW_(P), and go to step 4;

2) if N>0 and the UE chooses to decrement the counter, set N=N−1;

3) sense the channel for an additional slot duration, and if theadditional slot duration is idle, go to step 4; else, go to step 5;

4) if N=0, stop; else, go to step 2;

5) sense the channel until either a busy slot is detected within anadditional defer duration T_(d) or all the slots of the additional deferduration T_(d) are detected to be idle;

6) if the channel is sensed to be idle during all the slot durations ofthe additional defer duration T_(d), go to step 4; else, go to step 5.

In brief, Type 1 UL CAP of the UE described above may be summarized asfollows.

For uplink transmissions, a transmission node (e.g., a UE) may initiatea channel access procedure (CAP) to operate in the LAA Scell(s), whichare unlicensed band cells (S1210).

The UE may randomly select a backoff counter N within the contentionwindow CW according to step 1. At this time, N is set to an initialvalue N_(init) (S1220). N_(init) is selected as any value among thevalues between 0 and CW_(p).

Next, if the backoff counter value N is 0 in step 4 (S1230; Y), the UEterminates the CAP (S1232). Then, the eNB may perform a Tx bursttransmission (S1234). On the other hand, if the backoff counter value isnot 0 (S1230; N), the UE decrements the backoff counter value by 1according to step 2 (S1240).

Then, the UE checks whether the channel of the LAA SCell(s) is idle(S1250). If the channel is idle (S1250; Y), the base station checkswhether the backoff counter value is 0 (S1230).

On the contrary, if the channel is not idle in operation S1250 (S1250;N), namely, if the channel is busy, the UE checks whether the channel isidle during a defer duration Id (25 usec or more) longer than the slottime (e.g., 9 usec) (S1262). If the channel is idle during the deferduration (S1270; Y), the UE may resume the CAP.

For example, when the backoff counter value N_(init) is 10 and it isdetermined that the channel is busy after the backoff counter value isdecreased to 5, the UE senses the channel during the defer duration todetermine whether the channel is idle. If the channel is idle during thedefer duration, the UE may perform the CAP again from the backoffcounter value 5 (or from 4 after decrementing the backoff counter valueby 1) instead of setting the backoff counter value

On the other hand, if the channel is busy during the defer duration(S1270; N), the UE re-performs operation S1260 and checks again whetherthe channel is idle for a new defer duration.

If the UE has not transmitted a transmission including PUSCH on acarrier on which LAA Scell(s) transmission(s) are performed after step 4in the procedure above, the UE may transmit a transmission includingPUSCH on the carrier if the following conditions are met:

-   -   the channel is sensed to be idle at least in a slot duration        T_(sl) when the UE is ready to transmit the transmission        including PUSCH; and    -   the channel has been sensed to be idle during all the slot        durations of a defer duration T_(d) immediately before the        transmission including PUSCH.

On the other hand, if the channel has not been sensed to be idle in aslot duration T_(sl) when the UE first senses the channel after it isready to transmit, or if the channel has not been sensed to be idleduring any of the slot durations of a defer duration T_(d) immediatelybefore the intended transmission including PUSCH, the UE proceeds tostep 1 after sensing the channel to be idle during the slot durations ofa defer duration T_(d).

The defer duration T_(d) consists of duration T_(f) (=16 us) immediatelyfollowed by m_(p) consecutive slot durations where each slot durationT_(sl) is 9 us, and T_(f) includes an idle slot duration T_(sl) at thestart of T_(f).

A slot duration T_(sl) is considered to be idle if the UE senses thechannel during the slot duration, and the power detected by the UE forat least 4 us within the slot duration is less than energy detectionthreshold X_(Thresh). Otherwise, the slot duration T_(sl) is consideredto be busy.

CW_(min,p)≤CW_(p)≤CW_(max,p) is the contention window. CW_(p) adjustmentis described in detail in sub clause 3.2.2.

CW_(min,p) and CW_(max,p) and chosen before step 1 of the procedureabove.

m_(p), CW_(min,p), and CW_(max,p) are based on channel access priorityclass signaled to the UE (see Table 7).

X_(Thresh) is adjusted as described in sub clause 3.2.3.

3.2.1.2. Type 2 UL Channel Access Procedure

If the UL uses Type 2 channel access procedure for a transmissionincluding PUSCH, the UE may transmit the transmission including PUSCHimmediately after sensing the channel to be idle for at least a sensinginterval T_(short_ul)=25 us. T_(short_u) consists of a duration T_(f)=16us immediately followed by one slot duration T_(sl)=9 us and T_(f)includes an idle slot duration T_(sl) at the start of T_(f). The channelis considered to be idle for T_(short_ul) if it is sensed to be idleduring the slot durations of T_(short_ul).

3.2.2. Contention Window Adjustment Procedure

If the UE transmits transmissions using Type 1 channel access procedurethat are associated with channel access priority class p on a carrier,the UE maintains the contention window value CW_(P) and adjusts CW_(P)for those transmissions before step 1 of the procedure described in subclause 3.2.1.1 (i.e., before performing the CAP), using the followingprocedure:

-   -   if a NDI (New Data Indicator) value for at least one HARQ        process associated with HARQ_ID_ref is toggled,        -   for every priority class p∈{1,2,3,4}, set CW_(p)=CW_(min,p);    -   otherwise, increase CW_(P) for every priority class p∈{1, 2, 3,        4} to the next higher allowed value.

Here, HARQ_ID_ref is the HARQ process ID of UL-SCH in reference subframen_(ref). The reference subframe n_(ref) is determined as follows:

-   -   If the UE receives a UL grant in subframe n_(g), subframe n_(w)        is the most recent subframe before subframe n_(g)-3 in which the        UE has transmitted UL-SCH using Type 1 channel access procedure:        -   If the UE transmits transmissions including UL-SCH without            gaps starting with subframe no and in subframes n₀, n₁, . .            . , n_(w), reference subframe n_(ref) is subframe n₀;        -   otherwise, reference subframe n_(ref) is subframe n_(w).

The UE may keep the value of CW_(P) unchanged for every priority classp∈{1, 2, 3, 4}, if the UE scheduled to transmit transmissions withoutgaps including PUSCH in a set of subframes n₀, n₁, . . . , n_(w−1) usingType 1 channel access procedure, and if the UE is not able to transmitany transmission including PUSCH in the set of subframes.

The UE may keep the value of CW_(P) for every priority class p∈{1, 2, 3,4} the same as that for the last scheduled transmission including PUSCHusing Type 1 channel access procedure, if the reference subframe for thelast scheduled transmission is also n_(ref).

If CW_(p)=CW_(max,p), the next higher allowed value for adjusting CW_(p)is CW_(max,p).

If the CW_(p)=CW_(max,p) is consecutively used K times for generation ofN_(init), CW_(p) is reset to CW_(min,p) only for that priority class pfor which is consecutively used K times for generation of N_(init). K isselected by the UE from the set of values {1, 2, . . . , 8} for eachpriority class p∈{1, 2, 3, 4}.

3.2.3. Energy Detection Threshold Adaptation Procedure

A UE accessing a carrier on which LAA Scell(s) transmission(s) areperformed, shall set the energy detection threshold (X_(Thresh)) to beless than or equal to the maximum energy detection thresholdX_(Thresh_max).

The maximum energy detection threshold X_(Thresh_max) is determined asfollows:

-   -   if the UE is configured with higher layer parameter        ‘maxEnergyDetectionThreshold-r14’,        -   X_(Thresh_max) is set equal to the value signaled by the            higher layer parameter;    -   otherwise,        -   the UE shall determine X′_(Thresh_max) according to the            procedure described in sub clause 3.2.3.1;        -   if the UE is configured with higher layer parameter            ‘energyDetectionThresholdOffset-r14’,        -   X_(Thresh_max) is set by adjusting X′_(Thresh_max) according            to the offset value signaled by the higher layer parameter;    -   otherwise,        -   the UE shall set to X_(Thresh-max)=X′_(Thresh_max).

3.2.3.1. Default Maximum Energy Detection Threshold ComputationProcedure

If the higher layer parameter ‘absenceOfAnyOtherTechnology-r14’indicates TRUE:

${X_{{Thresh}\_\max}^{\prime} = {\min\begin{Bmatrix}{{T_{\max} + {10\mspace{14mu}{dB}}},} \\X_{r}\end{Bmatrix}}},$

-   -   where X_(r) is the maximum energy detection threshold defined by        regulatory requirements in dBm when such requirements are        defined, otherwise X_(r)=T_(max)+10 dB;

otherwise,

${X_{{Thresh}\_\max}^{\prime} = {\max\begin{Bmatrix}{{{- 72} + {{10 \cdot \log}\; 10\left( {{BWMHz}\text{/}20\mspace{14mu}{MHz}} \right){dBm}}},} \\{\min\begin{Bmatrix}{T_{\max},} \\{T_{\max} - T_{A} + \left( {P_{H} + {{10 \cdot \log}\; 10\left( {{BWMHz}\text{/}20\mspace{14mu}{MHz}} \right)} - P_{TX}} \right)}\end{Bmatrix}}\end{Bmatrix}}},$

-   -   where each variable is defined as follows:        -   T_(A)=10 dB        -   P_(H)=23 dBm;        -   P_(Tx) is the set to the value of P_(CMAX_H,c) as defined in            3GPP TS 36.101.        -   T_(max)(dBm)=10·log 10(3.16228·10⁻⁸ (mW/MHz)·BWMHz (MHz))            -   BWMHz is the single carrier bandwidth in MHz.

3.3. Sub-Frame Structure Applicable to LAA System

FIG. 13 is a diagram illustrating a partial TTI or a partial subframeapplicable to the present invention.

In the Release-13 LAA system, a partial TTI defined as DwPTS to make themost use of MCOT and support continuous transmission in transmitting aDL transmission burst is defined. The partial TTI (or partial subframe)refers to an interval in which a signal is transmitted only by a lengthless than the conventional TTI (e.g., 1 ms) in transmitting PDSCH.

In the present invention, for simplicity, a starting partial TTI or astarting partial subframe refers to a subframe in which some symbols inthe head part are left blank, and an ending partial TTI or an endingpartial subframe refers to a subframe in which some symbols in the tailpart are left blank (whereas a complete TTI is called a normal TTI or afull TTI).

FIG. 13 is a diagram illustrating various forms of the partial TTIdescribed above. In FIG. 13, the first block represents an endingpartial TTI (or subframe), and the second block represents a startingpartial TTI (or subframe). The third block of FIG. 13 represents apartial TTI (or subframe) having some symbols in the head and tail partsof a subframe left blank. Here, a time interval having no signaltransmission in a normal TTI is called a transmission gap (TX gap).

While FIG. 13 is based on the DL operation, the illustrated structurealso applicable to the UL operation in the same manner. For example, thepartial TTI structure shown in FIG. 13 is applicable to PUCCH and/orPUSCH transmission.

4. Proposed Embodiments

Hereinafter, configurations proposed in the present invention will bedescribed in detail based on the technical idea disclosed above.

As more and more communication devices require a greater communicationcapacity, efficient utilization of limited frequency bands in thewireless communication systems is increasingly becoming an importantrequirement. In this regard, cellular communication systems such as 3GPPLTE/NR systems support methods to utilize unlicensed bands such as the2.4 GHz band, which has been used mostly by the legacy WiFi systems, andunlicensed bands such as the 5 GHz and 60 GHz bands, which which arerecently drawn attention, for traffic off-loading.

As described above, in the unlicensed band, it is basically assumed thatwireless transmission and reception is performed through contentionbetween communication nodes. Accordingly, each communication node isrequired to check if no other communication node transmits a signal onthe channel by performing channel sensing before transmitting a signal.

This operation is called a listen-before-talk (LBT) procedure or achannel access procedure (CAP). In particular, the operation of checkingwhether other communication nodes perform signal transmission isreferred to as carrier sensing (CS). When it is determined through theCS that no other communication node performs signal transmission, it isdefined that clear channel assessment (CCA) has been confirmed.

A base station or a UE of an LTE/NR system to which the presentinvention is applicable is required to perform the LBT or CAP for signaltransmission in an unlicensed band (hereinafter referred to as aU-band). In addition, when the base station or the UE of the LTE/NRsystem transmits a signal, other communication nodes such as WiFi nodesshould cause interference by performing the LBT or CAP. For example, inthe WiFi standard (801.11ac), the CCA threshold is specified as −62 dBmfor non-WiFi signals and −82 dBm for WiFi signals. Therefore, the STA orthe AP may not perform signal transmission in order not to causeinterference when signals except for WiFi signals are received at thepower of −62 dBm or more.

According to the present invention, for UL data transmission of the UEin the U-band, the base station should succeed in the CAP (or LBT) forUL grant transmission in the U-band and the UE should also succeed inthe CAP (or LBT) for UL data transmission. That is, the UE can attemptUL data transmission only when both the base station and the UE succeedin the CAP (or the LBT).

In addition, in the LTE system, a delay of at least 4 msec is takenbetween the UL grant and the scheduled UL data. Accordingly, whenanother transmission node coexisting in the U-band for the correspondingtime period (e.g., delay time) obtains an access first, the scheduled ULdata transmission may be delayed. For this reason, various methods toincrease the efficiency of UL data transmission in the U-band are beingdiscussed.

In this regard, in the present invention, an autonomous UL transmission(hereinafter referred to as an auto_Tx or AUL transmission) method fortransmitting UL data without an UL grant will be described in detail.More specifically, the present invention provides a detailed descriptionof an activation and/or release method, CAP (or LBT) methods, transmitpower control methods, and the like for AUL transmission.

4.1. AUL Transmission Activation and/or Release Method

In configuring an AUL transmission in the U-band according to thepresent invention, the base station may preconfigure some information(e.g., a part or the entirety of periodicity, the number of subframes(SFs) valid for AUL transmission within a period, DM-RS sequenceinformation, modulation and coding scheme information, and a HARQprocess index) by RRC and/or higher layer signaling as in the case ofLTE semi-persistent scheduling (SPS), and may activate/or deactivate (orrelease) the AUL transmission by first layer ((L 1) signaling (e.g.,DCI).

FIG. 14 is a diagram schematically illustrating an AUL transmissionoperation of a UE according to the present invention.

As shown in FIG. 14, if the base station has performed activation of AULtransmission in SF #0 (or Slot #0, hereinafter relevant elements are allreferred to as SF #N for simplicity, wherein SF #N may be interpreted asSlot #N), the UE receiving the corresponding information may recognizeSFs for the AUL transmission based on the 5 ms periodicity and the 2 msduration, which are a preset periodicity and a preset duration, from SF#4. Then, when the UE performs and succeeds in the LBT (or CAP) for theSFs, the UE may attempt UL transmission without an additional UL grant.

Here, the duration information may be dynamically configured by L1signaling. Alternatively, the duration information may be dynamicallyconfigured by dynamically configuring, by L1 signaling, a maximum numberof SFs in which transmission is allowed within a duration preset by RRCsignaling.

Here, there may be a restriction that the set duration cannot be set tobe longer than the period (or period-k SFs or ms). For example, if theperiod is 5 ms (or 5 SFs), the maximum duration that can be set may be5-k SFs or ms (e.g., k=1).

The number of HARQ process indexes available for AUL transmission mayalso be set. Here, it may be necessary to apply a restriction that thenumber of HARQ process indexes available for the AUL transmission shouldbe larger than the maximum number of SFs in which transmission isallowed within the period. For example, it is assumed that the maximumnumber of SFs in which transmission is allowed within a specific periodis two and the number of HARQ process indexes for AUL transmission isone. In this case, the UE may transmit a plurality of SFs having thesame HARQ process index within the period, and accordingly the HARQprocedure may not operate efficiently.

For reference, DCI that activates and/or releases SPS in the legacy LTEsystem uses the same format as the conventional DCI scheduling DL and ULdata, but is differentiated by cyclic redundancy check (CRC) maskingwith different radio network temporary identifiers (RNTIs). That is, theUE may identify whether the DCI is DCI indicating activation and/orrelease of the SPS, based on the different CRC-masked RNTIs. In otherwords, when CRC checking is performed by the SPS-C-RNTI, the UE mayrecognize that the DCI is intended for SPS.

Table 8 below shows ‘special fields for semi-persistent schedulingactivation PDCCH/EPDCCH validation’ and Table 9 shows ‘special fieldsfor semi-persistent scheduling release PDCCH/EPDCCH validation’.

Additionally, the UE may validate whether the corresponding PDCCH/EPDCCHis intended for SPS activation and/or release, by presetting the valueof a specific field according to the DCI formats as shown in the tablesbelow. In addition, the new data indicator (NDI) is fixed to ‘0’ in theDCI for use in SPS activation and/or release. The NDI field may also beused for validation.

TABLE 8 DCI format DCI format 0 DCI format 1/1A 2/2A/2B/2C/2D TPCcommand for scheduled set to ‘00’ N/A N/A PUSCH Cyclic shift DM RS setto ‘000’ if present N/A N/A Modulation and coding scheme MSB is set to‘0’ N/A N/A and redundancy version HARQ process number N/A FDD: set to‘000’ FDD: set to ‘000’ TDD: set to ‘0000’ TDD. set to ‘0000’ Modulationand coding scheme N/A MSB is set to ‘0’ For the enabled transport block:MSB is set to ‘0’ Redundancy version N/A set to ‘00’ For the enabledtransport block: set to ‘00’

TABLE 9 DCI format 0 DCI format 1A TPC command for scheduled set to ‘00’N/A PUSCH Cyclic shift DM RS set to ‘000’ N/A if present Modulation andcoding scheme set to ‘11111’ N/A and redundancy version Resource blockassignment and Set to all ‘1’s N/A hopping resource allocation HARQprocess number N/A FDD: set to ‘000’ TDD: set to ‘0000’ Modulation andcoding scheme N/A set to ‘11111’ Redundancy version N/A set to ‘00’Resource block assignment N/A Set to all ‘1’s

In the Rel-14 LTE system, a new DCI format for UL scheduling in an LAASCell has been introduced in place of the conventional DCI formats 0/4.

More specifically, DCI formats 0A/0B are utilized for UL scheduling (inthe LAA SCell) of a UE for which transmission mode 1 (TM1) ortransmission of one transport block (TB) or one codeword (CW) isconfigured, and DCI formats 4A/4B are utilized for UL scheduling (in theLAA SCell) of the UE for which TM2 or transmission of 2 TBs or 2 CWs isconfigured. Here, DCI formats 0A/4A are DCI formats capable ofscheduling only a single SF and DCI formats 0B/4B are DCI formatscapable of scheduling multiple SFs (e.g., one or more SFs).

Here, the following fields are newly introduced to DCI formats0A/0B/4A/4B compared to the conventional DCI formats.

-   -   PUSCH trigger A: This field has value ‘0’ for non-triggered        scheduling and value ‘1’ for triggered scheduling, wherein the        triggered scheduling refers to a scheduling scheme in which the        PUSCH timing is not actually indicated through the corresponding        DCI, but is determined by a separately transmitted common PDCCH.    -   Timing offset: This field has a 4-bit-width. The field may        indicate a PUSCH timing offset from SF #n+4 to SF #n+19.    -   HARQ process number: This number is also signaled in a UL grant        according to introduction of asynchronous HARQ.    -   Redundancy version: This is also signaled in a UL grant due to        introduction of asynchronous HARQ.    -   PUSCH starting position: This field may signal the slot #0        boundary, the slot #1 boundary and a point between the        boundaries of slot #0 and slot #1 as a PUSCH starting position.        In general, the field may indicate a starting time of the PUSCH        region (e.g., a specific time between symbol indexes or symbol        boundaries) in a corresponding SF (or slot).    -   PUSCH ending position: This field may signal whether to leave        the last symbol blank in PUSCH transmission. In general, the        field may indicate an ending time of the PUSCH region (e.g., a        specific time between symbol indexes or symbol boundaries) in a        corresponding SF (or slot).    -   Channel access type: This field indicates one of the types of        channel access procedures allowed in the U-band. For example,        the field may indicate one of type 1 channel access based on a        random backoff or type 2 channel access for determining the        idle/busy state by performing CCA only for a certain time.    -   Channel access priority class: This field indicates one of four        channel access priority classes. The information indicated by        the field may be used in setting a defer period and a CWS.    -   Number of scheduled SFs: This field is present in Multi-SF (or        multi-slot) scheduling DCI (e.g., DCI format 0B/4B). The field        may indicate the number of actually scheduled SFs that is less        than or equal to a preset maximum number of schedulable SFs        (e.g., one of the values from 2 to 4 is set by RRC signalling).

Configurations proposed in the present invention based on the technicalcontents above are described below.

4.1.1. AUL Transmission Validation Method

The fields (e.g., TPC (Transmission Power Control), DMRS CS value, MCS,resource allocation) in DCI format 0A/0B/4A/4B which are identical tothose of the conventional DCI format 0/4 may be used for validation ofactivation and/or release of AUL transmission in the same manner as forthe conventional SPS activation and/or release. Additionally, the newlyadded fields described above may also be utilized for validation ofactivation and/or release for AUL transmission as described in theproposals (or part of the proposals) below.

-   -   PUSCH trigger A: This field may be fixed to ‘0’ (for validation        of activation and/or release of AUL transmission), assuming that        AUL transmission is generally scheduled by non-triggered        scheduling.    -   Timing offset: PUSCH timing for AUL transmission may be set by        an RRC configuration, and accordingly the field may be fixed to        a specific value (e.g., ‘0000’ or ‘1111’) (for validation of        activation and/or release of AUL transmission).    -   HARQ process number: This field may be fixed to ‘0000’ (for        validation of activation and/or release for AUL transmission),        similarly to DL SPS. Alternatively, the field may be used to        signal the number and/or range of HARQ process indexes to be        configured for AUL transmission. In this case, the field may not        be used for validation of activation. For example, when the        field indicating the HARQ process number indicates 4, the number        of HARQ process indexes configured for AUL transmission may be        4, and HARQ process indexes N/N+1/N+2/N+3 may be actually        configured for AUL transmission by the preset HARQ process index        starting value N.    -   Redundancy version: This field may be fixed to ‘00’ (for        validation of activation and/or release of AUL transmission),        similarly to DL SPS. Alternatively, when the field is configured        in I-bit per SF as in the case of DCI format 0B/4B, 1-bit        information per SF may be fixed to ‘0’ (for validation of        activation and/or release of AUL transmission).    -   PUSCH starting position: The PUSCH starting position for AUL        transmission may be set by the RRC configuration or be        predefined. Thus, the field may be fixed to a specific value        (e.g., ‘00’) (for validation of activation and/or release of AUL        transmission).    -   PUSCH ending position: The PUSCH ending position for AUL        transmission may be set by the RRC configuration or be        predefined. Thus, the field may be fixed to a specific value        (e.g., ‘0’ or ‘1’) (for validation of activation and/or release        of AUL transmission).    -   Channel access type: Basically, not all AUL transmissions can be        included within the channel occupancy time (COT) of the eNB.        Accordingly, type 1 channel access may be configured as a        default channel access procedure. Thus, the field may be fixed        to ‘0’ (for validation of activation and/or release of AUL        transmission).    -   Channel access priority class: One of the four channel access        priority classes may be configured by the RRC configuration or        be predefined. Thus, the field may be fixed to a specific value        (e.g., ‘00’ or ‘11’) (for validation of activation and/or        release of AUL transmission).    -   Number of scheduled SFs: The number of SFs (or slots) allowed        for AUL transmission within a specific period may be set by the        RRC configuration or be predefined. Thus, the field may be fixed        to a specific value (e.g., ‘0’ or ‘00’) (for validation of        activation and/or release of AUL transmission).

Additionally, the field for triggering an aperiodic SRS may also befixed to a specific value (e.g., ‘0’ or ‘00’) (for validation ofactivation and/or release of AUL transmission).

As an example applicable to the present invention, HARQ feedback of thebase station corresponding to AUL transmission may be introduced, andDCI newly defined for the HARQ feedback (hereinafter referred to as HARQDCI for simplicity) and (de)activation DCI for AUL transmission may bedefined to have an identical size (to reduce the number of times ofblind decoding (BD) of the UE). As a specific example, the HARQ DCI andthe (de)activation DCI for AUL transmission may be defined to have thesame size as DCI format 0A (or another DCI format).

In this case, the UE may distinguish between the two DCIs (the HARQ DCIand the (de)activation DCI for AUL transmission) by separate RNTIsallocated to the two DCIs. Alternatively, the UE may distinguish betweenthe two DCIs based on an indication of one of specific fields (e.g.,PUSCH trigger A, Timing offset, HARQ process number, Redundancy version,PUSCH starting position, PUSCH ending position, Channel access type,Channel access priority class, a field for triggering aperiodic SRS) inthe two DCIs. For example, to distinguish between the two DCIs, aspecific state of a specific field in the DCIs may indicate the HARQDCI, and the other specific state thereof may indicate the(de)activation DCI for AUL transmission. As a specific example, the‘channel access type’ field may indicate the HARQ DCI when the value ofthe field is ‘0’, and indicate the (de)activation DCI for AULtransmission when the value of the field is ‘1’. Alternatively, anotherfield may indicate the HARQ DCI when the value of the field is ‘0’, andindicate the (de)activation DCI for AUL transmission when the value ofthe field is ‘1’.

In addition, it may be necessary to identify whether the (de)activationDCI is activation DCI or deactivation DCI.

To this end, whether the DCI is deactivation DCI may be indicated by aspecific state which is not utilized for RB-interlace allocation.

Alternatively, whether the DCI is activation DCI or deactivation DCI maybe identify based on the value indicated by one of the fields (e.g.,PUSCH trigger A, Timing offset, HARQ process number, Redundancy version,PUSCH starting position, PUSCH ending position, Channel access type,Channel access priority class, the field for triggering aperiodic SRS).For example, the ‘PUSCH ending position’ field may indicate activationDCI when the value of the field is ‘0’, and indicate deactivation DCIwhen the value of the field is ‘1’. Alternatively, another field mayindicate activation DCI when the value of the field is ‘0’, and indicatedeactivation DCI when the value of the field is ‘1’.

Alternatively, whether the DCI is HARQ DCI/activation DCI/deactivationDCI may be identified based on the value of one of the fields (e.g.,PUSCH trigger A, Timing offset, HARQ process number, Redundancy version,PUSCH starting position, PUSCH ending position, Channel access type,Channel access priority class, the field for triggering aperiodic SRS).For example, a 2-bit field indicating the channel access priority classmay be used. The field may indicate that the DCI is HARQ DCI when thevalue thereof is ‘00’, and indicate that the DCI is deactivation DCIwhen the value thereof is ‘10’. Alternatively, another field mayindicate activation DCI when the value of the field is ‘0’, and indicatedeactivation DCI when the value of the field is ‘1’.

Alternatively, whether the DCI is HARQ DCI/activation DCI/deactivationDCI may be identified by configuring a new 2-bit format indicator fieldwhile maintaining the same size as one of the conventional DCI formats0A/0B/4A/4B. For example, the 2-bit format indicator field may indicateHARQ DCI when the value of the field is ‘00’, indicate activation DCIwhen the value of the field is ‘01’, and indicate deactivation DCI whenthe value of the field is ‘10’.

As another example applicable to the present invention, not only HARQfeedback information of the base station corresponding to the AULtransmission but also an MCS (and precoding matrix indicator (PMI))value may be indicated in the HARQ DCI.

In this case, whether the MCS (and PMI) is carried in the HARQ DCI (andwhether the MCS and/or the PMI are signaled for each HARQ process index)may be separately configured.

Alternatively, when it is assumed that the HARQ DCI maintains the samesize as at least one of the conventional DCI format 0A/0B/4A/4B(hereinafter referred to as DCI format X for simplicity), whether theMCS (and PMI) is carried in the HARQ DCI may be determined by the numberof HARQ process indexes allocated to AUL transmission and whether ULMIMO is supported. That is, if the number of HARQ process indexes isgreater than or equal to a specific (preset) number, or TM2 (or 2-TB)transmission is configured for the UE, HARQ feedback alone may besufficient for HARQ DCI configuration. Accordingly, in this case, theMCS (and PMI) may be configured not to be carried in the HARQ DCI. Onthe other hand, if the number of HARQ process indexes is less than thespecific (preset) number, or TM2 (or 2-TB) transmission is configuredfor the UE, information that is substantially included in the DCI may besufficiently smaller in size than DCI format X even if the MCS (and PMI)as well as HARQ feedback is included in the DCI. In this case, the MCS(and PMI) may be configured to be carried in the HARQ DCI.

When the MCS (and PMI) information is included in the HARQ DCI, the MCS(and PMI) information included in the HARQ DCI received in SF #n maybasically be applied to all HARQ process indexes configured for AULtransmission after SF #n+k (e.g., k=4). However, for an HARQ processindex which has not been flushed from the TX buffer (or for whichretransmission is ongoing) by the time of SF #n (or SF #n+k), the UE maynot update the MCS (and PMI) information received in SF #n until the TXbuffer is flushed. This is because the RB-interlace allocationinformation is changed by the activation DCI, and the transport blocksize (TBS) may be changed if only the MCS is changed for the fixednumber of RBs. Alternatively, for an HARQ process index that has notbeen flushed from the TX buffer (or for which retransmission is ongoing)by the time of SF #n (or SF #n+k), the UE may update and retransmit onlythe modulation order corresponding to the signaled MCS while maintainingthe TBS in the MCS information received in SF #n until the TX buffer isflushed.

The above-described various methods are configured for AUL transmission,but they may also be applied to HARQ process indexes for which(re)transmission is indicated through a UL grant. That is, for an HARQprocess index which has been configured for AUL transmission but forwhich (re)transmission has been instructed through the UL grant, the UEmay not update the MCS (and PMI) information received in SF #n until SF#n (or SF #n+k). Alternatively, for an HARQ process index which has beenconfigured for AUL transmission by the time of SF #n (or SF #n+k) butfor which (re)transmission is instructed through the UL grant, the UEmay update only the modulation order corresponding to the signaled MCSand attempt retransmission while maintaining the TBS in the MCSinformation received in SF #n.

In addition, if the MCS (and PMI) is indicated for each HARQ processindex, the above-described rule may be applied to each HARQ processindex.

4.1.2. L1 Signaling Method

Similar to SPS activation and/or release, which is allowed only for DCIformat 0 in the legacy LTE system, AUL transmission activation and/orrelease may be allowed only for DCI format 0A/0B (not for DCI format4A/4B) in the LAA SCell.

In the legacy LTE system, there is a restriction that SPI-related DCIshall be transmitted only in the PCell and SPS data shall also betransmitted in the PCell. However, in order to support AUL transmissionin the U-band, AUL transmission-related DCI needs to be transmitted aswell in a cell scheduling the U-band (e.g., LAA SCell).

Here, since the same DCI format as the conventional UL scheduling DCI isused for the DCI, the DCI needs to be distinguished by an RNTI valuemasking the CRC. For example, the DCI indicating activation and/orrelease of AUL transmission and/or retransmission of the AULtransmission may be CRC-scrambled by a separate RNTI (not the C-RNTI)configured for the UE.

If the UL scheduling cell is a U-band, the base station should performthe DL LBT (or CAP) for DCI transmission indicating activation and/orrelease of the AUL transmission and/or retransmission of the AULtransmission. Accordingly, if the base station fails in the LBT (orCAP), the base station may not attempt the DCI transmission.

Accordingly, in order to increase the success rate of the DCItransmission, AUL transmission may be allowed only when the ULscheduling cell is a licensed band cell (or PCell), not an LAA SCell. Inother words, AUL transmission may not be allowed if the UL schedulingcell is a U-band cell. Alternatively, the UE may not expect auto_Tx tobe configured for a UL scheduling cell which is a U-band.

When an AUL transmission is activated through multi-SF (or multi-slot)scheduling DCI (e.g., DCI format 0B), the number of SFs (or slots)corresponding to the value indicated by a field indicating the number ofscheduled SFs (or slots) may refer to the number of SFs (or slots) forAUL transmission allowed within a set period (configured by L1 signalingor higher layer signaling) or refer to the maximum number of SFs inwhich actual transmission is allowed among the SFs configured for theAUL transmission.

Here, the field indicating the number of scheduled SFs may not be usedfor validation of AUL transmission activation. For example, if theperiod of the AUL transmission is set to 5 ms by the RRC signaling andthe AUL transmission activation DCI indicates 2 as the number ofscheduled SFs, this may mean that AUL transmission is configured for 2ms with a 5 ms periodicity (e.g., SF #n/n+1/n+5/n+6 . . . ). In thiscase, activation of the AUL transmission through single SF (or slot)scheduling DCI (e.g., DCI format 0A) may mean that the number of SFs (orslots) for AUL transmission allowed within a set period is 1.Alternatively, when the period of AUL transmission is set to 5 ms andthe duration is set to 3 ms by RRC signaling, if the AUL transmissionactivation DCI indicates 2 as the number of scheduled SFs, the maximumnumber of SFs in which transmission can be performed for 3 ms may belimited to 2.

Alternatively, considering that the size of the DCI is large and theblocking probability may increase because the multi-SF scheduling DCImay be transmitted on (E)PDCCH having a high aggregation level to ensurestable transmission, AUL transmission activation and/or release throughthe multi-SF scheduling DCI may not be allowed. In other words, AULtransmission activation and/or release may be allowed only for single SF(or slot) scheduling DCI. In this case, the base station which hasfailed to receive the AUL transmission over the consecutive SFs may beallowed to instruct corresponding AUL retransmission through themulti-SF scheduling DCI. Here, the multi-SF scheduling DCI may beCRC-scrambled by a separate RNTI (not C-RNTI) configured for AULtransmission, and the NDI value may be set to 1. In other words, the UEmay not expect multi-SF scheduling DCI which is CRC-scrambled by aseparate RNTI (not C-RNTI) configured for AUL transmission and has theNDI value set to 0.

Considering the complexity of implementation of a UE that should performdetection of (E)PDCCH through many carriers in the legacy LTE system ifcarrier aggregation is performed on many carriers, signaling forreducing (E)PDCCH blind detection (BD) per cell/aggregation level andskipping BD of specific DCI has been introduced. Furthermore, signalingfor reducing BD per DCI format and skipping BD on LAA UL has beenintroduced.

If the number of times of BD is set to zero for DCI format(s) (e.g., DCIformat 0A) which are allowed for AUL transmission activation and/orrelease or the UE can skip the BD, the AUL transmission may not beconfigured for the UE. Accordingly, if AUL transmission is configuredfor a UE, the number of times of BD for DCI format(s) (e.g., DCI format0A) which are allowed for AUL transmission activation and/or release maybe set to a specific value (e.g., 1) or a specific ratio value (e.g.,0.5) with respect to an conventional BD value, even if the number oftimes of BD is set to zero for DCI format(s) or the BD can be skipped.

Alternatively, a UE for which the number of times of BD is set to zerofor the DCI format(s) (e.g., DCI format 0A) allowed for AUL transmissionactivation and/or release or the like or which is configured to skip theBD may be configured not to expect AUL transmission to be configured.

Alternatively, when there are multiple DCI formats allowed for AULtransmission activation and/or release, a UE for which AUL transmissionis configured may expect AUL transmission activation and/or release tobe performed in one of DCI formats to which the number of times of BDgreater than or equal to a specific value (e.g., 1) is assigned,according to a predetermined rule.

4.1.3. Other AUL Transmission Activation and/or Release Methods

All parameters (e.g., periodicity, the number of SFs valid for AULtransmission within a period, DM-RS sequence information, modulation andcoding scheme information, HARQ process index, resource allocation,etc.) which are necessary for AUL transmission may be configured by RRCsignaling, and AUL transmission activation and/or release may beindicated by 1-bit information alone in L1 signaling.

Specifically, the base station may simultaneously indicate activationand/or release of AUL transmission to multiple UEs through UE(group-)common DCI, or indicate the activation and/or release to each ofthe UEs according to the respective fields of the DCI which areassociated with the UEs.

For example, when UE group-common DCI for AUL transmission activationand/or release is configured in common for UE1 and UE2, the DCI may beconfigured to have a 2 bit-width, wherein the first bit of the two bitsmay be configured for auto_Tx activation and/or release for UE1, and thesecond bit may be configured for auto_Tx activation and/or release forUE2. Accordingly, UE 1 may recognize the DCI as indicating activation ofthe AUL transmission when the first bit information in the DCI is ‘1’,(or recognize the DCI as indicating release of the AUL transmission whenthe first bit information is ‘0’).

Alternatively, all parameters necessary for auto_Tx transmission andauto_Tx activation and/or release may be indicated only by L1 signaling(e.g., DCI format 0B) without configuration by separate RRC signaling(or without assistance from RRC signaling). In this case, at least DMRSCS, MCS, and HARQ process number fields among the proposed fields maynot be utilized for validation. The period information may be configuredby reinterpreting some fields (e.g., RV).

UL SFs (or slots or symbol groups) may be signaled through the UE(group-)common DCI. In this case, AUL transmission may be allowed onlythrough the UL SFs (or slot or symbol groups) signaled by the DCI. Inthis case, all parameters (e.g., periodicity, the number of SFs validfor AUL transmission within a period, DM-RS sequence information,modulation and coding scheme information, HARQ process index, resourceallocation, etc.) which are necessary for AUL transmission may bepreconfigured by RRC signaling.

For example, in the LAA system to which the present invention isapplicable, the base station may assign a part of the COT secured (oroccupied) after the LBT (or CAP) to the UE for UL operation. To thisend, the base station may signal information about the corresponding ULSFs on the common PDCCH. In addition, when the UE attempts ULtransmission included in the UL SFs signaled on the common PDCCH, the UEmay access a corresponding (unlicensed) channel with a little higherprobability using type 2 channel access.

In this case, in order to increase the transmission probability of theAUL transmission, auto_TX may be allowed only for the corresponding ULSFs (i.e., some SFs of the COT pre-secured by the base station). Here,among the indicated UL SFs, the SF region where the AUL transmissionwill be actually attempted by the UE may be configured differently foreach UE (preconfigured by higher layer signaling). For example, if fourcontiguous SFs are configured as the UL SFs, UE1 may be allowed toperform AUL transmission in the the first two SFs and UE2 may be allowedto perform AUL transmission in the last SF.

Additionally, in the LAA system, the base station may transmit 1-bitPUSCH trigger B capable of triggering a PUSCH triggered on the commonPDCCH (PDCCH indicating some SFs of the COT pre-secured by the basestation). If the PUSCH trigger B field is ON, most of the UL SFsconfigured on the common PDCCH may be filled with the triggered PUSCH.Accordingly, in this case, it may not be desirable to trigger AULtransmission. Thus, AUL transmission may be allowed in the indicated ULSFs only when PUSCH trigger B in the common PDCCH is OFF.

If there is no actual UL data when many AUL transmission resources areexcessively configured to increase the UL transmission efficiency, itmay be difficult for the base station to attempt signal transmissionalthough there are resources that can be skipped.

Accordingly, if the base station indicates the number of symbolsconstituting the DL SF of the next SF on the common PDCCH in order tosecure resources for DL data transmission, even the UEs may attempt DLreception even if the UEs have AUL transmission resources configured inthe next SF.

Alternatively, in the case where the base station signals, on the commonPDCCH, that a specific SF of a series of subsequent SFs or a region ofsome symbols in the specific SF is a DL SF or DL region, the UEs mayattempt DL reception even if the UEs have an AUL transmission resourceconfigured in the SF.

Alternatively, a UE that has been assigned DL data through UE-specificDL scheduling DCI may attempt to receive a DL signal in the SF even ifthere is an AUL transmission resource configured in the SF.

In addition, the UE of the LAA system may receive a configuration of aresource for measuring a received signal strength indicator (RSSI) valueduring a specific period/duration to report a RSSI measurement result.When the resource is defined as a RSSI measurement timing configuration(RMTC), the UEs may perform RSSI measurement without attempting AULtransmission, even if the UEs have an AUL transmission resourceconfigured in an SF overlapping with the RMTC interval.

4.1.4. Method for Configuring PUSCH Starting Position for AULTransmission

As a method for aligning starting positions of AUL transmission PUSCHsfor different UEs, the PUSCH starting positions may be configured by RRCsignaling or may be indicated by activation DCI (or HARQ feedback DCIfor AUL transmission of the base station).

Alternatively, the starting positions may be configured differentlyamong different UEs in consideration of time division multiplexing (TDM)between the UEs. To this end, different PUSCH starting positions for therespective UEs may be configured by RRC signaling or indicated by theactivation DCI (or HARQ feedback DCI for AUL transmission of the basestation), and may be determined differently for the respective UEsaccording to a preconfigured (UE-specific) rule.

In particular, when UL transmission can be performed through multipleLAA Scells (i.e., in the UL CA situation), the PUSCH starting positionsneed to be aligned in view of one UE. This is because, when it isassumed that the PUSCH starting position differs among the UL LAASCells, the same UE should perform UL transmission on a cell whileperforming the LBT operation (i.e., DL operation) for UL transmission onanother cell, but this operation requires the UE to have multiple RFchains. Accordingly, when one UE can perform UL transmission throughmultiple LAA SCells (i.e., in the UL CA situation), the UE may assumethat the PUSCH starting positions for AUL transmission corresponding tothe same SF are always configured/indicated to be identical if AULtransmission is configured through multiple UL LAA SCells for the UE.

In addition, PUSCH starting positions may be determined different forthe respective UEs according to a preconfigured (UE-specific) rule. Inthis case, the PUSCH starting positions may be determined as a functionof certain parameters (e.g., cell index, UE ID, SF index, etc.). Here,the certain parameters may refer to parameters irrelevant to the carrierindex.

4.2. LBT (or CAP) Method

In the LAA system, UL transmission is allowed after type 2 channelaccess of a UE if any one of the following conditions is satisfied:

-   -   UL transmission is included in the COT that is secured (or        occupied) by the base station;    -   UL SFs are configured on the carriers except for one carrier        randomly selected for UL SFs (for which the same PUSCH starting        position is indicated) among multiple carriers on which Type 1        channel access is configured; and    -   the gap between a UL transmission and a subsequent UL        transmission after the DL transmission is smaller than or equal        to a certain time (e.g., 25 us).

For UL transmission through AUL transmission configuration, transmissioncandidate UL SFs (or slots) may be periodically configured. Accordingly,it may not be easy that the above conditions are always satisfied.

According to the present invention, type 1 channel access based onrandom backoff may be basically performed for UL transmission throughAUL transmission configuration, and type 2 channel access may be allowedto be performed when any one of the above conditions is satisfied.

4.2.1. CWS Adjustment Method

For a random backoff-based channel access procedure (e.g., type 1channel access), the UE may select a random number within the CWS,decrement the number by 1 each time the channel is idle, and may accessthe channel when the number reaches 0. In addition, in order to lowerthe probability of collision with other nodes contending in the U-band,if the base station fails to receive data transmitted by the UE, the UEmay increase the CWS to lower the probability that other transmissionnodes will select the same random number.

More specifically, when the UE receives a UL grant in SF #n in the LAAsystem, the UE may configure the first (transmission) SF of the UL TXbursts including the latest UL SF before the (n-3)-th SF as a referenceSF. If initial transmission is indicated in the UL grant for at leastone TB with respect to an HARQ process ID corresponding to the referenceSF (or if the NDI value is toggled), the UE may initialize the CWSvalue. Otherwise, the CWS value is increased to the next value in apredetermined order.

According to the present invention, in performing the LBT (or channelaccess procedure) for AUL transmission, the UE may use the CWS valueadjusted by the PUSCH.

Alternatively, if the UE receives a retransmission UL grant with respectto the reference SF during AUL transmission, the UE may increase the CWSvalues corresponding to all channel access priority classes. In thiscase, the increased CWS values may be applied k ms (e.g., k=4) afterreceiving the UL grant.

The reference SF may refer to the first SF of UL transmission bursts (orcontinuous AUL transmission) that have started to be transmitted k1 ms(e.g., k1=4) before the time at which the UL grant (or HARQ DCI) isreceived. Alternatively, the reference SF may be defined differentlydepending on whether the UL grant is received or the HARQ DCI isreceived. As an example, when a UL grant is received, the reference SFmay refer to the first SF of the UL transmission bursts (transmittedafter type 1 channel access procedure) which have been scheduled by aseparate UL grant and started to be transmitted k1 ms (e.g., k1=4)before the time at which the UL grant is received. As another example,when HARQ DCI is received, the reference SF may refer to the first SF ofcontinuous AUL transmission (transmitted after type 1 channel accessprocedure) (or the UL transmission bursts corresponding to the HARQprocess indexes configured for the AUL transmission) that has started tobe transmitted kl ms (e.g., k1=4) before the time at which the HARQ DCIis received.

Alternatively, when the base station succeeds in receiving the AULtransmission, the base station may not transmit a UL grant correspondingto an HARQ process index indicating the reception. Therefore, in such acase, the UE may need to initialize the CWS values.

Accordingly, if there is no retransmission UL grant corresponding to theAUL transmission transmitted by the UE (or if no retransmission UL grantis received) for T ms (e.g., T=16 or the number of HARQ process indexesconfigured for AUL transmissions) after the AUL transmission (or thefirst transmission time of continuous AUL transmission), the UE mayinitialize CWS values corresponding to all channel access priorityclasses.

Alternatively, if there is neither a retransmission UL grant for the AULtransmission transmitted by the UE for T ms (e.g., T=16 or the number ofHARQ process indexes configured for AUL transmission) after the AULtransmission nor a retransmission UL grant for an AUL transmission (andPUSCH) transmitted for T ms (or if no retransmission UL grant isreceived), the UE may initialize the CWS values corresponding to allchannel access priority classes.

Alternatively, when it is assumed that the time taken until an AULtransmission having the same configured HARQ ID corresponding to theSF(s) of the AUL transmission transmitted by the UE (or the reference SFof the continuous AUL transmission) appears after the AUL transmissionSF(s) is T2 ms, the UE may initialize the CWS values corresponding toall channel access priority classes if the UE does not receive aretransmission UL grant for the SF(s) before T2−k2 ms (e.g., k2=4). Forexample, if HARQ process indexes corresponding to respective SFs arepredetermined, AUL transmission is transmitted in SF #n, and aretransmission UL grant for SF #n is not received k2 ms before SF#(n+T2) for which the same HARQ process index as that for SF #n isconfigured (i.e., in the duration from SF #n to SF #(n+T2)−k2), the UEmay initialize the CWS values corresponding to all channel accesspriority classes.

Alternatively, if the UE does not receive a retransmission UL grant forthe reference SF for the time corresponding to the maximum value betweenT ms and T2-k2 ms proposed above, the UE may initialize the CWS valuescorresponding to all channel access priority classes.

Alternatively, the base station may attempt to transmit DCI indicatingfailure of AUL transmission (e.g., DCI including a retransmission ULgrant or HARQ-ACK information), but fail to transmit the DCI because theUE continues to fail in the LBT (or channel access procedure). In thiscase, an operation (or action or mechanism) of the UE of increasing theCWS values may be needed.

As a method to perform this operation, the UE may increase the CWSvalues corresponding to all channel access priority classes if there isno DCI (e.g., DCI including a retransmission UL grant or HARQ-ACKinformation) corresponding to the AUL transmission transmitted by the UEfor T ms after the AUL transmission (or after the first transmissiontime of continuous AUL transmission) (for example, retransmission forthe AUL transmission may be triggered if there is no HARQ-ACK feedbackof the base station for the AUL transmission for T ms or T−K (e.g., K=4)ms).

Alternatively, the UE may increase the CWS values corresponding to allchannel access priority classes if there is neither DCI (e.g., DCIincluding a retransmission UL grant or HARQ-ACK information) for the AULtransmission transmitted by the UE for T ms after the AUL transmission(for example, retransmission for the AUL transmission may be triggeredif there is no HARQ-ACK feedback of the base station for the AULtransmission for T ms or T-K (e.g., K=4) ms), nor DCI for an AULtransmission (and PUSCH) transmitted for T ms.

Assuming that the base station transmits HARQ-ACK information for theAUL transmission of the UE to the UE, the UE may operate as follows.

First, when the UE receives an ACK for the HARQ process index of thereference SF, the UE may initialize the CWS values corresponding to allchannel access priority classes.

Alternatively, the UE may increase the CWS values corresponding to allchannel access priority classes when the UE receives NACK or DTX for theHARQ process index of the reference SF (wherein DTX means that the basestation has failed to receive the AUL transmission corresponding to theHARQ process index, and wherein the DTX may be signaled as one of theHARQ-ACK states or may be joint-coded with information (e.g., RV)different from the HARQ-ACK states and signaled). The increased orinitialized CWS values may be applied k ms (e.g., k=4) after the UEreceives a UL grant.

If the UE fails to receive a (valid) UL grant and HARQ DCI for T ms fromthe first SF of the AUL transmission (and/or the UL transmissionscheduled by the UL grant) (or from the SF in which the transmissionends) (or if the UE has received the UL grant and HARQ DCI for T ms butthe received UL grant and HARQ DCI are invalid), the UE may increase theCWS values corresponding to all channel access priority classes withrespect to AUL transmission (transmitted by performing the type 1channel access procedure) transmitted after T ms (and/or UL datascheduled by the UL grant). In this case, the UL grant or HARQ ACK maybe considered as an invalid UL grant or invalid HARQ DCI if at least oneof the following conditions is satisfied:

-   -   the UL grant and/or HARQ DCI are received within k2 ms (e.g.,        k2=3) from the first SF of the AUL transmission (and/or UL        transmission scheduled by the UL grant) (or the SF in which the        transmission ends);    -   the first SF (or last SF) of the transmission is an AUL        transmission SF and a UL grant is received for T ms after the        AUL transmission (or within T ms after k2 ms);    -   the first SF (or last SF) of the transmission is a UL        transmission scheduled through the UL grant and (AUL        transmission related) HARQ DCI is received for T ms after the UL        transmission (or within T ms after k2 ms);    -   the first SF (or last SF) of the transmission is a UL        transmission scheduled through the UL grant, (AUL transmission        related) HARQ DCI is received for T ms after the UL transmission        (or within T ms after k2 ms), and the HARQ DCI does not include        HARQ-ACK information corresponding to an HARQ process index        associated with the first SF (or last SF); and    -   the first SF (or last SF) of the transmission is a UL        transmission scheduled through the UL grant, (AUL transmission        related) HARQ DCI is received for T ms after the UL transmission        (or within T ms after k2 ms), and the HARQ DCI includes HARQ-ACK        information corresponding to an HARQ process index associated        with the first SF (or last SF), wherein the included information        is NACK.

Further, the UE may adjust the CWS as disclosed below according to thefollowing cases. The cases considered in the present invention are asfollows.

Case 1) The HARQ process index corresponding to the first SF of the ULTX bursts started at the time (i.e., SF #n-4) 4 SFs before SF #n inwhich the UE receives HARQ DCI is not configured for AUL transmission.

Case 2) The first SF of the UL TX bursts started at the time (i.e., SF#n-4) 4 SFs before SF #n in which the UE receives a UL grant is an AULtransmission.

Case 3) The HARQ process index corresponding to the first SF of the ULTX bursts started at the time (i.e., SF #n-4) 4 SFs before SF #n inwhich the UE receives HARQ DCI is configured for AUL transmission, butthe SF has been scheduled through a UL grant and the HARQ-ACKinformation corresponding to the HARQ process index included in the HARQDCI is NACK.

In Case 1 (or Case 2 or Case 3) as described above, the UE may increaseor maintain the CWS corresponding to all priority classes.

Alternatively, in Case 1, Case 2 or Case 3, the UE may consider areference SF positioned at an earlier time for adjustment of the CWSthan in the above-described embodiment.

More specifically, in Case 1, the SF of a UL TX burst in which the HARQprocess index corresponding to the first SF is configured for AULtransmission among the UL TX bursts started before SF #n-4 may bedefined as a reference SF, or the SF of a UL TX burst in which the HARQprocess index corresponding to the first SF is configured for AULtransmission among the UL TX bursts started before SF #n-4 and which isnot scheduled through a UL grant may be defined as a reference SF.

In Case 2, the SF of a UL TX burst in which the HARQ process indexcorresponding to the first SF is not configured for AUL transmissionamong the UL TX bursts started before SF #n-4 may be defined as areference SF, or the SF of a UL TX burst in which the HARQ process indexcorresponding to the first SF is configured for AUL transmission amongthe UL TX bursts started before SF #n-4 and which is scheduled through aUL grant may be defined as a reference SF.

Alternatively, in Case 1, the SF of a UL TX burst in which the HARQprocess index corresponding to the first SF is configured for AULtransmission among the UL TX bursts started before SF #n-4 may bedefined as a reference SF, or the SF of a UL TX burst in which the HARQprocess index corresponding to the first SF is configured for AULtransmission among the UL TX bursts started before SF #n-4 and which isnot scheduled through a UL grant may be defined as a reference SF.

As described above, if the UE does not receive a (valid) UL grant andHARQ DCI for T ms from the first SF of the AUL transmission (and/or theUL transmission scheduled by the UL grant) (or from the SF in which thetransmission ends) (or if the UE has received the UL grant and HARQ DCIfor T ms but the received UL grant and HARQ DCI are invalid), the UE mayincrease the CWS corresponding to all channel access priority classesfor AUL transmission (transmitted by performing the type 1 channelaccess procedure) (and/or UL data scheduled by the UL grant) transmittedT ms after the first SF (or the SF in which the transmission ends).

More specifically, the UE may operate a timer for each UL TX burst andincrement the timer value in SF units (or msec) from the reference SF(e.g., the first SF of the corresponding UL TX burst or the SF in whichthe transmission ends).

If there is any timer whose value is greater than or equal to T (orgreater than T) when the UE performs the LBT (or channel accessprocedure) for AUL transmission (transmitted by performing the type 1channel access procedure) (and/or UL data scheduled by a UL grant), theUE may increase or maintain the CWS corresponding to all priorityclasses. After increasing the CWS, the UE may reset a timer having thegreatest value that is greater than or equal to T (or greater than T).If the UE receives a (valid) UL grant and HARQ DCI, the UE may reset allthe timer values to zero.

FIGS. 15 and 16 are diagrams schematically illustrating an operation ofadjusting a contention window size (CWS) of a UE according to thepresent invention.

As an example, as shown in FIG. 15, the UE may increase Timer #1 fromthe AUL transmission burst started in SF #0 (or Slot #0, hereinafterrelevant elements are all referred to as SF #N for simplicity, whereinSF #N may be interpreted as Slot #N), and increase Timer #2 from the AULburst started in SF #2. Then, when the UE discovers (receives) HARQ DCIin SF #6, the UE may reset the two timers.

As another example, as shown in FIG. 16, the UE may increase Timer #1from the AUL burst started in SF #0 (or Slot #0, hereinafter relevantelements are all referred to as SF #N for simplicity, wherein SF #N maybe interpreted as Slot #N), and increase Timer #2 from the AUL burststarted in SF #2. Thereafter, when the UE attempts to perform AULtransmission by performing Type 1 channel access procedure in SF #10 andT=8 ms, the UE may increase the CWS values and reset Timer #1 becauseTimer #1 is greater than T. Then, when the UE attempts to additionallyperform AUL transmission by performing Type 1 channel access procedurein SF #12, there is a Timer #2 larger than T, and the UE may increasethe CWS value (i.e., increase the CWS value twice compared to the CWSfor SF #2 AUL transmission) and reset Timer #2 because Timer #2 islarger than T.

In the present invention, the base station may configure specific HARQprocess number(s) for AUL transmission and schedule, through a dynamicUL grant, UL transmissions corresponding to not only the HARQ processnumber not allocated for AUL transmission but also the HARQ processnumber allocated for AUL transmission. Alternatively, the base stationmay be allowed to operate as described above.

For example, even though HARQ ID #0 is allocated for the AULtransmission among the 16 HARQ process numbers, the base station mayschedule the PUSCH corresponding to HARQ ID #0 through the dynamic ULgrant.

Further, HARQ feedback of the base station corresponding to AULtransmission may be introduced. Hereinafter, for simplicity, DCI for theHARQ feedback is referred to as HARQ DCI.

The HARQ DCI may be configured to always include HARQ-ACK informationcorresponding to the HARQ ID(s) configured for AUL transmission. If SF#n transmission for UL (re)transmission corresponding to an HARQ IDallocated for AUL transmission is scheduled through a dynamic UL grantand HARQ DCI is received after a certain time (e.g., SF #n+3) (when theSF is a reference SF), the UE may adjust the CWS as follows using theHARQ-ACK information corresponding to the HARQ ID of the reference SF inthe HARQ DCI.

In this operation, the UE may not utilize the HARQ-ACK information inperforming CWS adjustment since the UL (re)transmission is triggeredthrough the dynamic UL grant (Method 1). In other words, the UE maymaintain the CWS corresponding to all priority classes irrespective ofthe HARQ-ACK information.

Alternatively, the UE may consider only ACK information of the HARQ-ACKinformation corresponding to the HARQ ID as valid (Method 2). In otherwords, the UE may initialize the CWS value corresponding to all priorityclasses if the HARQ-ACK information corresponding to the HARQ ID is ACK,and maintain the CWS corresponding to all priority classes if theHARQ-ACK information is NACK.

In addition, if SF #n transmission for UL (re)transmission correspondingto an HARQ ID allocated for AUL transmission is scheduled through adynamic UL grant, and HARQ DCI and the dynamic UL grant corresponding tothe HARQ ID are received after a certain time (e.g., SF #n+3) (when thecorresponding SF is a reference SF), the UE may adjust the CWS asfollows using the HARQ-ACK information corresponding to the HARQ ID ofthe reference SF in the HARQ DCI in temporal order of the HARQ DCI andthe dynamic UL grant.

If the HARQ DCI is received (for example, in SF #n+4) and the dynamic ULgrant is subsequently received (for example, in SF #n+5), the UE mayadjust the CWS by applying Method 1 or Method 2 described above.

On the other hand, if the dynamic UL grant is received (for example, inSF #n+4) and the HARQ DCI is subsequently received (for example, in SF#n+5), the UE may consider the HARQ-ACK information in the HARQ DCIcorresponding to the HARQ ID as invalid.

In this case, the UE may expect that the ACK/NACK information in theHARQ DCI will not be different from the NDI toggle information in the ULgrant.

Alternatively, if the two pieces of information are different from eachother, the UE may preferentially take into consideration one of the HARQDCI information or the NDI information in the UL grant.

For example, the UE may prioritize information that precedes between theHARQ DCI and UL grant in temporal order, or prioritize one of the HARQDCI and UL grant that is later in temporal order.

Alternatively, which of the HARQ DCI and the UL grant is prioritized bythe UE may be configured differently depending on whether the HARQ DCIinformation is ACK/NACK. For example, the UE may prioritize the HARQ DCI(namely, unconditionally consider the NDI of the HARQ DCI as toggled) ifthe HARQ DCI corresponds to ACK, and prioritize the UL grant if the HARQDCI corresponds to NACK.

Alternatively, the UE may conservatively perform retransmission if anyone of the HARQ DCI and the UL grant indicates retransmission. As aspecific example, the UE may recognize the transmission as a newtransmission (initial transmission) only when the HARQ DCI is ACK andthe UL grant is NDI toggle, and recognize the transmission asretransmission in the other cases.

4.2.2. Configuring Channel Access Priority Class

As described above, in the LAA system, four UL channel access priorityclasses are defined, and a defer duration (defer period), allowed CWSvalues, the maximum allowed COT, and the like are set for each priorityclass.

In this case, the channel access priority class value for AULtransmission may be fixed to a specific value (e.g., priority class 1)or may be configured by RRC signaling.

Alternatively, the channel access priority class value for AULtransmission may be set via the AUL transmission activation DCI. In thiscase, the field indicating a priority class in the DCI may not be usedfor validation of AUL transmission activation.

Alternatively, the channel access priority class value for AULtransmission may be determined according to the number of SFs (or slots)(or transmission time) in which transmission will be actually performed,the duration of an AUL transmission configured within a period, or themaximum number of SFs in which transmission may be performed within theduration. For example, if the duration of the AUL transmission (or themaximum number of SFs in which transmission may be performed within theduration) set in the period is 3 ms, the channel access priority classvalue for the AUL transmission may be set to priority class 2, which islarger than or equal to the duration and has the smallest the MCOT,based on Table 7. Alternatively, if the duration of the AUL transmission(or the maximum number of SFs in which transmission may be performedwithin the duration) is set to 3 ms for the UE, but the UE fails in theLBT (or channel access procedure) for the first SF and thus actuallyperforms transmission in only two SFs, the UE may set LBT parameters,considering the channel access priority class value for AUL transmissionas priority class 1.

Alternatively, the channel access priority class value for the AULtransmission may be set by the periodicity of the AUL transmission. Forexample, if the period is shorter than or equal to P ms, the UE mayperform the LBT (or channel access procedure) excessively frequently,which may increase the number of transmission attempts compared to theattempts made by other transmission nodes that contend with the UE.Accordingly, in the above case, a relatively higher priority class maybe assigned as the channel access priority class value for the AULtransmission. As another example, if the period is longer than P ms, arelatively small priority class may be assigned as the channel accesspriority class value for the AUL transmission. As an example applicableto the present invention, priority class 3 may be assigned as thechannel access priority class value for the AUL transmission when theperiod is shorter than 10 ms, and priority class 1 may be assigned asthe channel access priority class value for the AUL transmission whenthe period is longer than or equal to 10 ms. More generally, priorityclass Y may be assigned as the channel access priority class value forthe AUL transmission if the period is less than X, and priority class Zmay be assigned as the channel access priority class value for the AULtransmission if the period is greater than X, where Y> Z may besatisfied.

4.2.3. Methods of Signaling Remaining COT in Case of UE-Initiated COT

In the Rel-14 eLAA system, a part of the channel occupancy time (COT)occupied by the base station may be handed over to the UE, and an LBTtype (Type 2 channel access procedure) capable of starting transmissionif the channel is idle only for a certain time may be indicated to theUE. In response, the UE recognizing that a part of the COT is handedover thereto may switch to the Type 2 CAP (that is, perform the Type 2CAP instead of Type 1 CAP indicated through the UL grant) and perform ULtransmission even when Type 1 channel access procedure (CAP) isindicated to the UE through the UL grant.

In this case, since the UE autonomously selects a channel accesspriority class for the AUL transmission of the UE, only the UE may knowthe value of the COT that the UE occupies after the LBT. Accordingly, itmay be necessary to signal to the base station how long the UE hasoccupied the COT, or how much of the COT has remained. Accordingly, amethod of signaling the COT value occupied by the UE will be describedin detail below.

4.2.3.1. First Signaling Method

The UE may signal to the base station the COT value remaining accordingto occupancy and how much of the corresponding COT is to be occupied bythe UE. For example, if the (maximum) COT value that the UE occupiesafter performing Type 1 CAP for AUL transmission is 8 SFs and the UE isto perform the AUL transmission for 3 SFs, the UE may signal 8 and 3 tothe base station at the same time. In addition, for the signaling, thevalues may be counted down during continuous AUL transmission andsignaled in each SF. Thus, according to the previous example, the UE maysignal 8 and 3 in the latest SF and signal 7 and 2 in the next SF inwhich the AUL transmission is performed.

4.2.3.2. Second Signaling Method

The UE may signal, to the base station, the ending time (offset) of theAUL transmission and the remaining COT value (duration) from the endingtime. For example, when the UE starts the AUL transmission from SF #nafter performing Type 1 CAP for AUL transmission, and the (maximum)occupied COT is 8 SFs and the UE is to perform AUL transmission for 3SFs in the future, the UE may signal 3, which is the offset value, and5, which is the duration value, to the base station at the same time.For the signaling, the offset value may be counted down duringcontinuous AUL transmission and signaled in each SF. Accordingly,according to the previous example, the UE may signal 2, which is theoffset value, and 5, which is the duration value, to the base stationsimultaneously in the next AUL transmission SF, SF #n+1.

In this case, there may be a restriction that the base station receivingthe COT-related signaling of the UE is allowed to start DL transmissionk SFs (e.g., k=3) after the last SF of the AUL transmission occupied bythe UE. In addition, the base station may receive the COT-relatedsignaling from multiple UEs. In this case, the base station may consideronly the overlapping time between the COTs of the UEs (or the entiretime corresponding to the union of the COTs of the UEs) as a COT sharedwith the UEs, and thus may perform an LBT (or CAP) allowing transmissionto be started if the channel is idle only for a certain time as LBT (orCAP) for DL transmission that is transmitted within the overlappingtime.

4.2.4. LBT Method Used when PUSCH and AUL Transmission are ArrangedConsecutively

FIG. 17 is a diagram illustrating the operation of a UE according to anembodiment of the present invention.

As shown in the example of FIG. 17, if an AUL transmission having a 5 msperiod and a 2 ms duration is triggered through activation DCItransmitted in SF #0 (or Slot #0, hereinafter relevant elements are allreferred to as SF #N for simplicity, wherein SF #N may be interpreted asSlot #N) (or if an AUL transmission resource is configured using othermethods, such as a bit-map), UL data may be scheduled in SF #8.

If UL data should always be transmitted for AUL transmission UL SFsconfigured in the U-band, the base station scheduling SF #8 mayindicate, in the UL grant (or through the UL grant), the priority classvalue that is set considering the 3 ms COT.

However, it may be inefficient for the UE to transmit UL data in all theconfigured AUL transmission SFs in terms of operation of the U-band.This is because the operation of the UE of performing the LBT (or CAP)for UL transmission and transmitting a kind of dummy data when UL datato be actually transmitted is not stored in the UE buffer only appliesinterference to other nodes and does not contribute to improvement ofthe system performance. Accordingly, for the configured AUL transmissionUL SFs, the UE may perform transmission if there is data to be actuallytransmitted and skip the UL SFs (i.e., skip UL transmission in the ULSFs) otherwise.

If the UE can skip the above operation, it may be difficult for the basestation scheduling SF #8 in the example of FIG. 17 to check whether ULdata is transmitted in SF #9 and SF #10. Accordingly, the base stationmay indicate priority class 1, in which a maximum of 2 ms is allowed asthe MCOT, in the UL grant (or through the UL grant).

However, in the above case, when the UE receiving the UL grant succeedsin the LBT (or CAP) using the LBT parameters corresponding to priorityclass 1, UL transmission may be allowed only in SF #8 and SF #9 and maynot be allowed in SF #10 (even if there is UL data to be transmitted inSF #9 and SF #10). Hereinafter, methods to address this issue will bedescribed.

(Method 1)

Even if the priority class value is indicated as 1 in a UL grant for SF#8, the UE to attempt AUL transmission in SF #9 and SF #10 may attemptthe LBT (or CAP) using LBT parameters corresponding to priority class 2in which a maximum of 3 ms is ensured as the MCOT.

(Method 2)

The UE may be configured to always perform a new LBT (or CAP) before AULtransmission starts even when UL SFs are contiguously configured for adynamically scheduled PUSCH and the AUL transmission. That is, even ifthe UE has succeeded in the previous LBT (or CAP) immediately before SF#8, the UE may transmit the UL SFs for the AUL transmission from thetime at which the UE attempts and succeeds in the LBT (or CAP) againafter the UL transmission in SF #8. In response, the base station mayset the PUSCH starting position of the first SF of the AUL transmissionto be later than the SF boundary. In this case, if the UE succeeds inthe LBT (or CAP) during the gap between the SF boundary and the setPUSCH starting position, the UE may successfully transmit the first SFof the AUL transmission as well.

(Method 3)

After transmitting as many UL SFs as the MCOT corresponding to thepriority class (indicated in the UL grant) based on the previouslyattempted LBT (or CAP), the UE may attempt a new LBT (or CAP) for theremaining auto_Tx transmission. For example, in the example of FIG. 17,for the UE having attempted UL transmission since SF #8, the 2 mstransmission may be guaranteed to the maximum because the priority classvalue indicated in the UL grant is 1. Accordingly, after the UE performsa UL transmission in SF #8 and SF #9, the UE may perform a new LBT (orCAP) to attempt transmission of UL SFs for the next AUL transmission.

Methods 1 to 3 described above may be generally applied even to a casewhere a PUSCH is scheduled without a timing gap prior to a preconfiguredAUL transmission resource. For example, in FIG. 17, the base station mayschedule a PUSCH for SF #9 through the UL grant. In this case, when theUE transmits the PUSCH and an AUL transmission for SF #10, methods 1 to3 described above may be applied.

When the UE determines the priority class for the AUL transmission basedon the type of UL data present in the buffer of the UE, a PUSCH may bescheduled without a timing gap prior to a preconfigured AUL transmissionresource as described above. In this case, a different rule may beapplied according to the relation between the priority class indicatedfor the PUSCH (hereinafter referred to as scheduled UL (SUL) forsimplicity) and the priority class determined for the AUL transmissionby the UE.

More specifically, it is assumed that X is indicated in the UL grant asthe priority class for the SUL and the UE determines Y as the priorityclass for AUL transmission.

In this case, when X<Y, UL data traffic with a lower priority appearslater, and accordingly the UE may perform transmissions by prioritizingthe SUL and then perform an LBT (or CAP) for AUL transmission.Alternatively, in performing an LBT (or CAP) for SUL, the UE may utilizeLBT parameters (e.g., defer period, minimum CWS, maximum CWS, etc.)corresponding to priority class Y (or a priority class higher than Y)for the LBT (or CAP). If the UE succeeds in the LBT (or CAP) (ifpriority class Y is smaller than the MCOT), continuous transmission maybe performed without any additional LBT (or CAP) (or continuoustransmission may be allowed for the UE without any additional LBT).

When X=Y, both priorities are the same, and accordingly continuoustransmission may be allowed without any additional LBT (or CAP) if thesum of the transmission times of the SUL and AUL transmission is smallerthan the MCOT corresponding to priority class X. If the sum of thetransmission times of the SUL and the AUL transmission is larger thanthe MCOT corresponding to priority class X for the UE, the UE mayperform transmissions by prioritizing the SUL and then perform an LBT(or CAP) for the AUL transmission.

When X>Y, UL data traffic with a higher priority appears later, andaccordingly continuous transmission may be allowed without anyadditional LBT (or CAP) if the sum of the transmission times of the SULand the AUL transmission is smaller than the MCOT corresponding topriority class X. Alternatively, since the both priority classes aredifferent from each other, the UE may perform transmissions byprioritizing the SUL and then perform an LBT (or CAP) for the AULtransmission.

FIG. 18 is a diagram illustrating the operation of the UE according toanother embodiment of the present invention.

Unlike the example of FIG. 17, the PUSCH may be scheduled after the AULtransmission as in FIG. 18. In this case, the base station is notcertain of UL transmission in SF #9 (or slot #9, hereinafter referred toas SF #N for simplicity, wherein SF #N may be interpreted as slot #N)and SF #10, and accordingly the base station may indicate priority class1 in the UL grant (or through the UL grant) scheduling UL transmissionin SF #11.

In this case, the UE may pre-perform an LBT (or CAP) for the AULtransmission in SF #9 without knowing that the PUSCH may be scheduled inSF #11. In particular, the LBT (or CAP) may be an LBT (or CAP) that isnot allowed for 3 ms continuous transmission from SF #9 to SF #11. Inthis case, the UE may change the priority class to priority class 2 forthe 3 ms continuous transmission as in Method 1 described above.However, this operation may not be easy in UE implementation.Accordingly, to address the issue as described above, the presentinvention proposes the following methods.

(Method A)

The UE may prioritize the UL transmission in SF #11, and thus may alwaysleave the last n symbols of SF #10 blank to perform a new LBT (or CAP)for the UL transmission in SF #11 during the n symbols. The value of nmay be predetermined or may be set through separate signaling.Alternatively, the value of n may be determined based on the priorityclass indicated in SF #11. In particular, for a smaller priority class,n may be set to a smaller value.

(Method B)

The UE may prioritize transmission of AUL transmission. Thus, the UE maystart a new LBT (or CAP) for SF #11 after completing UL transmission inSF #10.

Whether the UE will use (or perform) Method A or Method B may beconfigured by higher layer signaling.

Alternatively, if transmission on 7 or fewer symbols in 1 SF consistingof 14 symbols is configured for the UE, the UE may apply Method B.Otherwise, the UE may apply Method A.

For example, in Method A and/or Method B described above may be appliedonly when the gap between the time of the UL grant and the first SF ofthe AUL transmission is smaller than or equal to Y ms (e.g., Y=4).

Methods A and B described above may be generally applied when a PUSCH isscheduled without a timing gap following a AUL transmission resourcepreconfigured for the UE. For example, in FIG. 17, the base station mayschedule a PUSCH for SF #10 through the UL grant. When the UE transmitsthe PUSCH and an AUL transmission for SF #9, the UE may apply Method Aor Method B.

When the UE determines the priority class for the AUL transmission basedon the type of UL data present in the buffer of the UE, a PUSCH may bescheduled without a timing gap following a preconfigured AULtransmission resource as described above. In this case, a different rulemay be applied according to the relation between the priority classindicated for the PUSCH (SUL) and the priority class determined for theAUL transmission by the UE.

More specifically, it is assumed that X is determined as the priorityclass for the AUL transmission and Y is indicated through the UL grantas the priority class for the SUL.

In this case, when X<Y, In this case, when X<Y, UL data traffic with alower priority appears later, and accordingly the UE may performtransmissions by prioritizing the AUL transmission and then perform anLBT (or CAP) for SUL transmission. Alternatively, the UE may prioritizethe SUL transmission and may thus terminate the AUL transmission nsymbols earlier than the ending time in order to provide an LBT gap forthe SUL. Alternatively, in performing an LBT (or CAP) for the AULtransmission, the UE may utilize LBT parameters (e.g., defer period,minimum CWS, maximum CWS, etc.) corresponding to priority class Y (or apriority class higher than Y) for the LBT (or CAP). If the UE succeedsin the LBT (or CAP) (if priority class Y is smaller than the MCOT),continuous transmission may be performed without any additional LBT (orCAP) (or continuous transmission may be allowed for the UE without anyadditional LBT).

When X=Y, both priorities are the same, and accordingly continuoustransmission may be allowed without any additional LBT (or CAP) if thesum of the transmission times of the SUL and AUL transmission is smallerthan the MCOT corresponding to priority class X. If the sum of thetransmission times of the SUL and the AUL transmission is larger thanthe MCOT corresponding to priority class X for the UE, the UE mayperform transmissions by prioritizing the AUL transmission and thenperform an LBT (or CAP) for the SUL transmission. Alternatively, the UEmay prioritize the SUL transmission and may thus terminate the AULtransmission n symbols earlier than the ending time in order to providean LBT gap for the corresponding SUL.

When X>Y, UL data traffic with a higher priority appears later, andaccordingly continuous transmission may be allowed without anyadditional LBT (or CAP) if the sum of the transmission times of the SULand the AUL transmission is smaller than the MCOT corresponding topriority class X. Alternatively, since the both priority classes aredifferent from each other, the UE may perform transmissions byprioritizing the AUL transmission and then perform an LBT (or CAP) forthe SUL transmission. Alternatively, the UE may prioritize the SULtransmission and thus terminate the AUL transmission n symbols earlierthan the ending time in order to provide an LBT gap for the SUL.

4.3. Transmit Power Control (TPC) Methods

In the legacy LTE system, TPC for the SPS UL SF has been performedthrough the TPC field in the UL grant and DCI format 3/3A. However, TPCthrough DCI format 3/3A does not apply to the SCell, and accordingly itmay not be easy to apply TPC to AUL transmission through a closed loop.Hereinafter, TPC methods to address this issue will be described indetail.

4.3.1. First TPC Method

The UE may simultaneously apply PUSCH TPC through DCI format 3/3A toboth the PCell (or PSCell) and the LAA SCell.

Alternatively, the UE may apply the PUSCH TPC through DCI format 3/3Aonly to the LAA SCell having AUL transmission configured therefor.

Alternatively, the UE may apply the PUSCH TPC through DCI format 3/3A tothe LAA SCell only if the PCell (or PSCell) and the LAA SCell belong tothe same timing advance group (TAG).

4.3.2. Second TPC Method

In an example applicable to the present invention, a field correspondingto TPC for the LAA SCell may be newly defined in DCI format 3/3Atransmitted on the PCell.

For example, for DCI format 3/3A including M TPC commands, command M1may be configured as a TPC command for the PCell of UE1, command M2 maybe configured as a TCP command for LAA SCell #1 of UE1, and command M3may be configured as a TCP command for LAA SCell #2 of UE1. In thiscase, a TPC command corresponding to an LAA SCell may be applied tomultiple LAA SCells which are configured for the UE (and in which AULtransmission is configured). Specifically, there may be one TPC commandcorresponding to the LAA SCell configured for a specific UE, and the TPCcommand may be commonly applied to all LAA SCells which are configuredfor the UE (and in which AUL transmission is configured).

This method may be applied only when the PCell and the LAA SCell belongto different TAGs.

4.3.3. Third TPC Method

In another example applicable to the present invention, UE(group-)common DCI for TPC to be transmitted in a U-band (e.g., LAASCell) may be introduced. For this purpose, similar to the case of DCIformat 3/3A, a rule may be predefined such that a TPC command at aspecific position among M TPC commands is applied to the UE. In thiscase, the UE may apply the corresponding TPC command only to the LAASCell in which the DCI has been transmitted (and AUL transmission isconfigured), or may apply the TPC command to all LAA SCells which areconfigured (and in which AUL transmission is configured) in common.

Additionally, in performing the LBT (or CAP) for the UL SFs configuredfor AUL transmission, if a channel access priority class ispreconfigured, a higher power offset value may be set for a lowerpriority class value, considering (or recognizing) UL data for the lowerpriority class value as more urgent. For example, 6 dB power boost maybe configured for priority class 1 and 3 dB power boost may beconfigured for priority class 2.

FIG. 19 is a flowchart illustrating a method for transmitting an uplinksignal from a UE through a U-band according to an embodiment of thepresent invention.

In the time domain, the UE receives downlink control information (DCI)for scheduling uplink transmission immediately after activated AUL(autonomous uplink) transmission (S1910). For simplicity, the uplinktransmission scheduled through the DCI is referred to as scheduleduplink (SUL) transmissions.

Subsequently, the UE performs the AUL transmission and the SULtransmission through the U-band based on a first method or a secondmethod (S1920).

For example, when the UE performs the AUL transmission and the SULtransmission based on the first method, the UE may terminate ongoing AULtransmission a certain time interval before the SUL transmission andperform the SUL transmission (S1930).

Here, the certain time interval may correspond to an N (where N is anatural number) symbol interval. As a specific example, one symbol, twosymbols, or fourteen symbols (i.e., one subframe or one slot) may beapplied as the N symbols.

In more detail, when the UE performs the AUL transmission and the SULtransmission based on the first method, the UE may perform the AULtransmission based on a first channel access procedure (CAP) for the AULtransmission and the SUL transmission based on a second CAP for the SULtransmission.

As another example, when the UE performs the AUL transmission and theSUL transmission based on the second method, the UE may perform the AULtransmission and the SUL transmission continuously (S1940).

Here, the UE may perform the AUL transmission and the SUL transmissionbased on the second method when the following conditions are satisfied:

-   -   A priority class for the AUL transmission is larger than or        equal to a priority class for the SUL transmission;    -   a sum of lengths of the AUL transmission and the SUL        transmission is smaller than a maximum channel occupancy time        (MCOT) corresponding to the priority class for the AUL        transmission

In more detail, when the UE performs the AUL transmission and the SULtransmission based on the second method, the UE may perform the AULtransmission and the SUL transmission continuously based on a channelaccess procedure (CAP) for the AUL transmission.

FIG. 20 is a flowchart illustrating a method for transmitting an uplinksignal from a UE through a U-band according to another embodiment of thepresent invention.

The UE performs an activated first autonomous uplink (AUL) transmissionthrough the U-band (S2010).

Then, when the UE does not receive when downlink control information(DCI) including an uplink grant scheduling uplink transmission oracknowledgement information during a certain time after the first AULtransmission, the UE increases contention window sizes (CWSs)corresponding to all channel access priority classes (S2020).

Then, the UE performs active second AUL transmission through the U-bandbased on the increased CWSs (S2030).

Here, the DCI may correspond to DCI including an uplink grant forscheduling a retransmission with respect to the first AUL transmissionor acknowledgment information with respect to the first AULtransmission.

In addition, the certain time may correspond to one or more subframes.

Additionally, when the first AUL transmission or the second AULtransmission is performed in a plurality of cells, starting positions ofthe first AUL transmission or the second AUL transmission in theplurality of cells may be configured to be identical.

In the configuration above, the UE may operate as follows.

The UE may perform the first AUL transmission based on a first channelaccess procedure (CAP) for the first AUL transmission. The UE mayperform the second AUL transmission based on a second CAP, to which theincreased CWSs are applied, for the second AUL transmission.

In the method for performing uplink transmission from the UE through theU-band as illustrated in FIGS. 19 and 20, a first DCI activating aspecific AUL transmission (e.g., the first AUL transmission) and asecond DCI releasing the specific AUL transmission (e.g., the first AULtransmission) may be distinguished from a third DCI includingacknowledgment information corresponding to the specific AULtransmission (e.g., the first AUL transmission) based on a value of afirst field.

As an example, the first field may correspond to a physical uplinkshared channel (PUSCH) trigger A field, which is defined in the 3GPP TS36.212 standard. As another example, the first field may correspond toanother field defined in the 3GPP TS 36.212 standard.

In addition, the first DCI may be distinguished from the second DCIbased on a value of a second field. As an example, the second field maycorrespond to a timing offset field defined in the 3GPP TS 36.212standard. As another example, the second field may correspond to anotherfield defined in the 3GPP TS 36.212 standard.

In the configurations above, the first DCI, the second DCI, and thethird DCI may have an identical size.

In addition, the first DCI, the second DCI, and the third DCI may bescrambled by a radio network temporary identifier (RNTI) different froma cell-C-RNTI.

Since each embodiment of the above-described proposed method can beconsidered as one method for implementing the present invention, it isapparent that each embodiment can be regarded as a proposed method. Inaddition, the present invention can be implemented not only using theproposed methods independently but also by combining (or merging) someof the proposed methods. In addition, it is possible to define a rulethat information on whether the proposed methods are applied (orinformation on rules related to the proposed methods) should betransmitted from the eNB to the UE through a predefined signal (e.g.,physical layer signal, higher layer signal, etc.).

5. Device Configuration

FIG. 21 is a diagram illustrating configurations of a UE and a basestation capable of being implemented by the embodiments proposed in thepresent invention. The UE and the base station shown in FIG. 21 operateto implement the above-described embodiments of the method of uplinksignal transmission/reception between the UE and the base station.

A UE 1 may act as a transmission end on a UL and as a reception end on aDL. A base station (eNB or gNB) 100 may act as a reception end on a ULand as a transmission end on a DL.

That is, each of the UE and the base station may include a Transmitter(Tx) 10 or 110 and a Receiver (Rx) 20 or 120, for controllingtransmission and reception of information, data, and/or messages, and anantenna 30 or 130 for transmitting and receiving information, data,and/or messages.

Each of the UE and the base station may further include a processor 40or 140 for implementing the afore-described embodiments of the presentdisclosure and a memory 50 or 150 for temporarily or permanently storingoperations of the processor 40 or 140.

The UE configured as described above may operate as follows.

In an example, the UE 1 receives, through the receiver 20, downlinkcontrol information (DCI) scheduling uplink transmission immediatelyafter activated autonomous uplink (AUL) transmission, in the timedomain. Then, the UE 1 performs the AUL transmission and the uplinktransmission through the U-band based on a first method or a secondmethod, using the transmitter 10.

Here, the first method corresponds to a method that the UE terminatesongoing AUL transmission a certain time interval before the uplinktransmission and performs the uplink transmission, and the second methodcorresponds to a method that the UE performs the AUL transmission andthe uplink transmission continuously.

In another example, the UE 1 performs activated first autonomous uplink(AUL) transmission through the U-band, using the transmitter 10. Then,when the UE 1 fails to receive downlink control information (DCI)comprising an uplink grant scheduling uplink transmission oracknowledgement information during a certain time after the first AULtransmission, the UE 1 increases contention window sizes (CWSs)corresponding to all channel access priority classes through theprocessor 40. Then, the UE 1 performs activated second AUL transmissionthrough the U-band based on the increased CWSs, using the transmitter10.

The Tx and Rx of the UE and the base station may perform a packetmodulation/demodulation function for data transmission, a high-speedpacket channel coding function, OFDM packet scheduling, TDD packetscheduling, and/or channelization. Each of the UE and the base stationof FIG. 21 may further include a low-power Radio Frequency(RF)/Intermediate Frequency (IF) module.

Meanwhile, the UE may be any of a Personal Digital Assistant (PDA), acellular phone, a Personal Communication Service (PCS) phone, a GlobalSystem for Mobile (GSM) phone, a Wideband Code Division Multiple Access(WCDMA) phone, a Mobile Broadband System (MBS) phone, a hand-held PC, alaptop PC, a smart phone, a Multi Mode-Multi Band (MM-MB) terminal, etc.

The smart phone is a terminal taking the advantages of both a mobilephone and a PDA. It incorporates the functions of a PDA, that is,scheduling and data communications such as fax transmission andreception and Internet connection into a mobile phone. The MB-MMterminal refers to a terminal which has a multi-modem chip built thereinand which can operate in any of a mobile Internet system and othermobile communication systems (e.g. CDMA 2000, WCDMA, etc.).

Embodiments of the present disclosure may be achieved by various means,for example, hardware, firmware, software, or a combination thereof.

In a hardware configuration, the methods according to exemplaryembodiments of the present disclosure may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the methods according to theembodiments of the present disclosure may be implemented in the form ofa module, a procedure, a function, etc. performing the above-describedfunctions or operations. A software code may be stored in the memory 50or 150 and executed by the processor 40 or 140. The memory is located atthe interior or exterior of the processor and may transmit and receivedata to and from the processor via various known means.

Those skilled in the art will appreciate that the present disclosure maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent disclosure. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of thedisclosure should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein. It is obvious to those skilled in the art thatclaims that are not explicitly cited in each other in the appendedclaims may be presented in combination as an embodiment of the presentdisclosure or included as a new claim by a subsequent amendment afterthe application is filed.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to various wireless access systemsincluding a 3GPP system, and/or a 3GPP2 system. Besides these wirelessaccess systems, the embodiments of the present disclosure are applicableto all technical fields in which the wireless access systems find theirapplications. Moreover, the proposed method can also be applied tommWave communication using an ultra-high frequency band.

The invention claimed is:
 1. A method performed by a user equipment (UE)operating in a wireless communication system, the method comprising:performing an autonomous uplink (AUL) transmission starting before timeunit n using a channel access procedure (CAP) on a unlicensed band,wherein n is an integer; and performing a scheduled uplink (SUL)transmission starting from the time unit n on the unlicensed band,wherein depending on whether a priority class value for channel accessfor the AUL transmission is equal to or larger than a priority classvalue for channel access for the SUL transmission, the SUL transmissionstarts from the time unit n either without a gap or with a gap after theAUL transmission, such that: based on the priority class value forchannel access for the AUL transmission not being equal to or largerthan the priority class value for channel access for the SULtransmission: the AUL transmission is terminated, while the AULtransmission is ongoing and before the AUL transmission ends, with thegap before the time unit n at which the SUL transmission starts.
 2. Themethod of claim 1, wherein the time unit n is one of: a first time unitwhere a first time interval configured for the AUL transmission overlapswith a second time interval scheduled for the SUL transmission, or asecond time unit following a third time unit configured for the AULtransmission.
 3. The method of claim 1, wherein the gap comprises one ormore symbols.
 4. The method of claim 1, wherein based on the priorityclass value for channel access for the AUL transmission being equal toor larger than the priority class value for channel access for the SULtransmission: the SUL transmission starts from the time unit n withoutthe gap after the AUL transmission ends such that the SUL transmissionis performed without the CAP for the SUL transmission.
 5. The method ofclaim 1, wherein the AUL transmission is activated based on a firstdownlink control information (DCI), and wherein the AUL transmission isreleased based on a second DCI.
 6. The method of claim 5, wherein thefirst DCI is distinguished from the second DCI based on a value of afirst field of the first DCI and a value of a first field of the secondDCI, and wherein the first field of the first DCI and the first field ofthe second DCI are timing offset fields.
 7. The method of claim 6,wherein a second field of the first DCI and a second field of the secondDCI have an identical value, and wherein a second field of a third DCIfor acknowledgement of the AUL transmission has a different value fromthe second field of the first DCI and the second field of the secondDCI.
 8. The method of claim 7, wherein the second field of the firstDCI, the second field of the second DCI, and the second field of thethird DCI are physical uplink shared channel (PUSCH) trigger A fields.9. The method of claim 7, wherein the first DCI, the second DCI and thethird DCI have an identical size.
 10. The method of claim 7, wherein thefirst DCI, the second DCI and the third DCI are scrambled by a radionetwork temporary identifier (RNTI) different from a cell-RNTI (C-RNTI).11. The method of claim 1, wherein based on the priority class value forchannel access for the AUL transmission being equal to or larger thanthe priority class value for channel access for the SUL transmission:the SUL transmission starts from the time unit n without the gap afterthe AUL transmission such that the SUL transmission starts from the timeunit n without a listen-before-talk (LBT) gap after the AULtransmission.
 12. The method of claim 1, wherein a sum of a duration ofthe AUL transmission and a duration of the SUL transmission does notexceed a maximum channel occupancy time (MCOT) for the AUL transmission.13. The method of claim 1, wherein based on the priority class value forchannel access for the AUL transmission being equal to or larger thanthe priority class value for channel access for the SUL transmission:the SUL transmission starts from the time unit n without gap after theAUL transmission ends.
 14. A user equipment (UE) configured to operatein a wireless communication system, the UE comprising: a transceiver; atleast one processor; and at least one computer memory operablyconnectable to the at least one processor and storing instructions that,when executed by the at least one processor, perform operationscomprising: performing, through the transceiver, an autonomous uplink(AUL) transmission starting before time unit n using a channel accessprocedure (CAP) on a unlicensed band, wherein n is an integer; andperforming, through the transceiver, a scheduled uplink (SUL)transmission starting from the time unit n on the unlicensed band,wherein depending on whether a priority class value for channel accessfor the AUL transmission is equal to or larger than a priority classvalue for channel access for the SUL transmission, the SUL transmissionstarts from the time unit n either without a gap or with a gap after theAUL transmission, such that: based on the priority class value forchannel access for the AUL transmission not being equal to or largerthan the priority class value for channel access for the SULtransmission: the AUL transmission is terminated, while the AULtransmission is ongoing and before the AUL transmission ends, with thegap before the time unit n at which the SUL transmission starts.
 15. Acommunication device configured to operate in a wireless communicationsystem, the communication device comprising: at least one processor; andat least one memory operably connectable to the at least one processorand storing instructions that, when executed by the at least oneprocessor, perform operations comprising: performing an autonomousuplink (AUL) transmission starting before time unit n using a channelaccess procedure (CAP) on a unlicensed band, wherein n is an integer;and performing a scheduled uplink (SUL) transmission starting from thetime unit n on the unlicensed band, wherein depending on whether apriority class value for channel access for the AUL transmission isequal to or larger than a priority class value for channel access forthe SUL transmission, the SUL transmission starts from the time unit neither without a gap or with a gap after the AUL transmission, suchthat: based on the priority class value for channel access for the AULtransmission not being equal to or larger than the priority class valuefor channel access for the SUL transmission: the AUL transmission isterminated, while the AUL transmission is ongoing and before the AULtransmission ends, with the gap before the time unit n at which the SULtransmission starts.